String matching
You are encouraged to solve this task according to the task description, using any language you may know.
Basic Data Operation
This is a basic data operation. It represents a fundamental action on a basic data type.
You may see other such operations in the Basic Data Operations category, or:
Integer Operations
Arithmetic |
Comparison
Boolean Operations
Bitwise |
Logical
String Operations
Concatenation |
Interpolation |
Comparison |
Matching
Memory Operations
Pointers & references |
Addresses
- Task
Given two strings, demonstrate the following three types of string matching:
- Determining if the first string starts with second string
- Determining if the first string contains the second string at any location
- Determining if the first string ends with the second string
Optional requirements:
- Print the location of the match for part 2
- Handle multiple occurrences of a string for part 2.
- Metrics
- Counting
- Word frequency
- Letter frequency
- Jewels and stones
- I before E except after C
- Bioinformatics/base count
- Count occurrences of a substring
- Count how many vowels and consonants occur in a string
- Remove/replace
- XXXX redacted
- Conjugate a Latin verb
- Remove vowels from a string
- String interpolation (included)
- Strip block comments
- Strip comments from a string
- Strip a set of characters from a string
- Strip whitespace from a string -- top and tail
- Strip control codes and extended characters from a string
- Anagrams/Derangements/shuffling
- Word wheel
- ABC problem
- Sattolo cycle
- Knuth shuffle
- Ordered words
- Superpermutation minimisation
- Textonyms (using a phone text pad)
- Anagrams
- Anagrams/Deranged anagrams
- Permutations/Derangements
- Find/Search/Determine
- ABC words
- Odd words
- Word ladder
- Semordnilap
- Word search
- Wordiff (game)
- String matching
- Tea cup rim text
- Alternade words
- Changeable words
- State name puzzle
- String comparison
- Unique characters
- Unique characters in each string
- Extract file extension
- Levenshtein distance
- Palindrome detection
- Common list elements
- Longest common suffix
- Longest common prefix
- Compare a list of strings
- Longest common substring
- Find common directory path
- Words from neighbour ones
- Change e letters to i in words
- Non-continuous subsequences
- Longest common subsequence
- Longest palindromic substrings
- Longest increasing subsequence
- Words containing "the" substring
- Sum of the digits of n is substring of n
- Determine if a string is numeric
- Determine if a string is collapsible
- Determine if a string is squeezable
- Determine if a string has all unique characters
- Determine if a string has all the same characters
- Longest substrings without repeating characters
- Find words which contains all the vowels
- Find words which contain the most consonants
- Find words which contains more than 3 vowels
- Find words whose first and last three letters are equal
- Find words with alternating vowels and consonants
- Formatting
- Substring
- Rep-string
- Word wrap
- String case
- Align columns
- Literals/String
- Repeat a string
- Brace expansion
- Brace expansion using ranges
- Reverse a string
- Phrase reversals
- Comma quibbling
- Special characters
- String concatenation
- Substring/Top and tail
- Commatizing numbers
- Reverse words in a string
- Suffixation of decimal numbers
- Long literals, with continuations
- Numerical and alphabetical suffixes
- Abbreviations, easy
- Abbreviations, simple
- Abbreviations, automatic
- Song lyrics/poems/Mad Libs/phrases
- Mad Libs
- Magic 8-ball
- 99 bottles of beer
- The Name Game (a song)
- The Old lady swallowed a fly
- The Twelve Days of Christmas
- Tokenize
- Text between
- Tokenize a string
- Word break problem
- Tokenize a string with escaping
- Split a character string based on change of character
- Sequences
11l
<lang 11l>print(‘abcd’.starts_with(‘ab’)) print(‘abcd’.ends_with(‘zn’)) print(‘bb’ C ‘abab’) print(‘ab’ C ‘abab’) print(‘abab’.find(‘bb’) ? -1) print(‘abab’.find(‘ab’) ? -1)</lang>
- Output:
1B 0B 0B 1B -1 0
360 Assembly
<lang 360asm>* String matching 04/04/2017 STRMATCH CSECT
USING STRMATCH,R15
XPRNT SS,L'SS
CLC SS(L'S1),S1
BNE NOT1
XPRNT =C'-- STARTS WITH',14
XPRNT S1,L'S1
NOT1 EQU *
CLC SS+L'SS-L'S2(L'S2),S2
BNE NOT2
XPRNT =C'-- ENDS WITH',12
XPRNT S2,L'S2
NOT2 EQU *
LA R0,L'SS-L'S3+1
LA R1,SS
LOOP CLC 0(L'S3,R1),S3
BNE NOT3
XPRNT =C'-- CONTAINS',11
XPRNT S3,L'S3
NOT3 LA R1,1(R1)
BCT R0,LOOP
BR R14
SS DC CL6'ABCDEF' S1 DC CL2'AB' S2 DC CL2'EF' S3 DC CL2'CD' PG DC CL80' '
YREGS
END STRMATCH</lang>
- Output:
ABCDEF -- STARTS WITH AB -- ENDS WITH EF -- CONTAINS CD
AArch64 Assembly
<lang AArch64 Assembly> /* ARM assembly AARCH64 Raspberry PI 3B */ /* program strMatching64.s */
/*******************************************/ /* Constantes file */ /*******************************************/ /* for this file see task include a file in language AArch64 assembly*/ .include "../includeConstantesARM64.inc" /*******************************************/ /* Initialized data */ /*******************************************/ .data szMessFound: .asciz "String found. \n" szMessNotFound: .asciz "String not found. \n" szString: .asciz "abcdefghijklmnopqrstuvwxyz" szString2: .asciz "abc" szStringStart: .asciz "abcd" szStringEnd: .asciz "xyz" szStringStart2: .asciz "abcd" szStringEnd2: .asciz "xabc" szCarriageReturn: .asciz "\n" /*******************************************/ /* UnInitialized data */ /*******************************************/ .bss /*******************************************/ /* code section */ /*******************************************/ .text .global main main:
ldr x0,qAdrszString // address input string ldr x1,qAdrszStringStart // address search string bl searchStringDeb // Determining if the first string starts with second string cmp x0,0 ble 1f ldr x0,qAdrszMessFound // display message bl affichageMess b 2f
1:
ldr x0,qAdrszMessNotFound bl affichageMess
2:
ldr x0,qAdrszString // address input string ldr x1,qAdrszStringEnd // address search string bl searchStringFin // Determining if the first string ends with the second string cmp x0,0 ble 3f ldr x0,qAdrszMessFound // display message bl affichageMess b 4f
3:
ldr x0,qAdrszMessNotFound bl affichageMess
4:
ldr x0,qAdrszString2 // address input string ldr x1,qAdrszStringStart2 // address search string bl searchStringDeb // cmp x0,0 ble 5f ldr x0,qAdrszMessFound // display message bl affichageMess b 6f
5:
ldr x0,qAdrszMessNotFound bl affichageMess
6:
ldr x0,qAdrszString2 // address input string ldr x1,qAdrszStringEnd2 // address search string bl searchStringFin cmp x0,0 ble 7f ldr x0,qAdrszMessFound // display message bl affichageMess b 8f
7:
ldr x0,qAdrszMessNotFound bl affichageMess
8:
ldr x0,qAdrszString // address input string ldr x1,qAdrszStringEnd // address search string bl searchSubString // Determining if the first string contains the second string at any location cmp x0,0 ble 9f ldr x0,qAdrszMessFound // display message bl affichageMess b 10f
9:
ldr x0,qAdrszMessNotFound // display substring result bl affichageMess
10:
100: // standard end of the program
mov x0,0 // return code mov x8,EXIT // request to exit program svc 0 // perform system call
qAdrszMessFound: .quad szMessFound qAdrszMessNotFound: .quad szMessNotFound qAdrszString: .quad szString qAdrszString2: .quad szString2 qAdrszStringStart: .quad szStringStart qAdrszStringEnd: .quad szStringEnd qAdrszStringStart2: .quad szStringStart2 qAdrszStringEnd2: .quad szStringEnd2 qAdrszCarriageReturn: .quad szCarriageReturn /******************************************************************/ /* search substring at begin of input string */ /******************************************************************/ /* x0 contains the address of the input string */ /* x1 contains the address of substring */ /* x0 returns 1 if find or 0 if not or -1 if error */ searchStringDeb:
stp x1,lr,[sp,-16]! // save registers stp x2,x3,[sp,-16]! // save registers mov x3,0 // counter byte string ldrb w4,[x1,x3] // load first byte of substring cbz x4,99f // empty string ?
1:
ldrb w2,[x0,x3] // load byte string input cbz x2,98f // zero final ? cmp x4,x2 // bytes equals ? bne 98f // no not find add x3,x3,1 // increment counter ldrb w4,[x1,x3] // and load next byte of substring cbnz x4,1b // zero final ? mov x0,1 // yes is ok b 100f
98:
mov x0,0 // not find b 100f
99:
mov x0,-1 // error
100:
ldp x2,x3,[sp],16 // restaur 2 registers ldp x1,lr,[sp],16 // restaur 2 registers ret // return to address lr x30
/******************************************************************/ /* search substring at end of input string */ /******************************************************************/ /* x0 contains the address of the input string */ /* x1 contains the address of substring */ /* x0 returns 1 if find or 0 if not or -1 if error */ searchStringFin:
stp x1,lr,[sp,-16]! // save registers
stp x2,x3,[sp,-16]! // save registers
stp x4,x5,[sp,-16]! // save registers
mov x3,0 // counter byte string
// search the last character of substring
1:
ldrb w4,[x1,x3] // load byte of substring cmp x4,#0 // zero final ? add x2,x3,1 csel x3,x2,x3,ne // no increment counter //addne x3,#1 // no increment counter bne 1b // and loop cbz x3,99f // empty string ?
sub x3,x3,1 // index of last byte
ldrb w4,[x1,x3] // load last byte of substring
// search the last character of string
mov x2,0 // index last character
2:
ldrb w5,[x0,x2] // load first byte of substring cmp x5,0 // zero final ? add x5,x2,1 // no -> increment counter csel x2,x5,x2,ne //addne x2,#1 // no -> increment counter bne 2b // and loop cbz x2,98f // empty input string ? sub x2,x2,1 // index last character
3:
ldrb w5,[x0,x2] // load byte string input cmp x4,x5 // bytes equals ? bne 98f // no -> not found subs x3,x3,1 // decrement counter blt 97f // ok found subs x2,x2,1 // decrement counter input string blt 98f // if zero -> not found ldrb w4,[x1,x3] // load previous byte of substring b 3b // and loop
97:
mov x0,1 // yes is ok b 100f
98:
mov x0,0 // not found b 100f
99:
mov x0,-1 // error
100:
ldp x4,x5,[sp],16 // restaur 2 registers ldp x2,x3,[sp],16 // restaur 2 registers ldp x1,lr,[sp],16 // restaur 2 registers ret // return to address lr x30
/******************************************************************/ /* search a substring in the string */ /******************************************************************/ /* x0 contains the address of the input string */ /* x1 contains the address of substring */ /* x0 returns index of substring in string or -1 if not found */ searchSubString:
stp x1,lr,[sp,-16]! // save registers stp x2,x3,[sp,-16]! // save registers stp x4,x5,[sp,-16]! // save registers mov x2,0 // counter byte input string mov x3,0 // counter byte string mov x6,-1 // index found ldrb w4,[x1,x3]
1:
ldrb w5,[x0,x2] // load byte string cbz x5,99f // zero final ? cmp x5,x4 // compare character beq 2f mov x6,-1 // no equals - > raz index mov x3,0 // and raz counter byte add x2,x2,1 // and increment counter byte b 1b // and loop
2: // characters equals
cmp x6,-1 // first characters equals ? csel x6,x2,x6,eq // yes -> index begin in x6 //moveq x6,x2 // yes -> index begin in x6 add x3,x3,1 // increment counter substring ldrb w4,[x1,x3] // and load next byte cmp x4,0 // zero final ? beq 3f // yes -> end search add x2,x2,1 // else increment counter string b 1b // and loop
3:
mov x0,x6 b 100f
98:
mov x0,0 // not found b 100f
99:
mov x0,-1 // error
100:
ldp x4,x5,[sp],16 // restaur 2 registers ldp x2,x3,[sp],16 // restaur 2 registers ldp x1,lr,[sp],16 // restaur 2 registers ret // return to address lr x30
/********************************************************/ /* File Include fonctions */ /********************************************************/ /* for this file see task include a file in language AArch64 assembly */ .include "../includeARM64.inc" </lang>
Action!
<lang Action!>BYTE FUNC FindS(CHAR ARRAY text,sub BYTE start)
BYTE i,j,found
i=start
WHILE i<=text(0)-sub(0)+1
DO
found=0
FOR j=1 TO sub(0)
DO
IF text(i+j-1)#sub(j) THEN
found=0 EXIT
ELSE
found=1
FI
OD
IF found THEN
RETURN (i)
FI
i==+1
OD
RETURN (0)
BYTE FUNC StartsWith(CHAR ARRAY text,sub)
BYTE pos
pos=FindS(text,sub,1) IF pos=1 THEN RETURN (1) FI
RETURN (0)
BYTE FUNC EndsWith(CHAR ARRAY text,sub)
BYTE pos,start
IF sub(0)>text(0) THEN RETURN (0) FI start=text(0)-sub(0)+1 pos=FindS(text,sub,start) IF pos=start THEN RETURN (1) FI
RETURN (0)
BYTE FUNC Contains(CHAR ARRAY text,sub
BYTE ARRAY positions) BYTE pos,count
pos=1 count=0
WHILE pos<=text(0)
DO
pos=FindS(text,sub,pos)
IF pos>0 THEN
positions(count)=pos
count==+1
pos==+1
ELSE
EXIT
FI
OD
RETURN (count)
PROC TestStartsWith(CHAR ARRAY text,sub)
IF StartsWith(text,sub) THEN
PrintF("""%S"" starts with ""%S"".%E",text,sub)
ELSE
PrintF("""%S"" does not start with ""%S"".%E",text,sub)
FI
RETURN
PROC TestEndsWith(CHAR ARRAY text,sub)
IF EndsWith(text,sub) THEN
PrintF("""%S"" ends with ""%S"".%E",text,sub)
ELSE
PrintF("""%S"" does not end with ""%S"".%E",text,sub)
FI
RETURN
PROC TestContains(CHAR ARRAY text,sub)
BYTE ARRAY positions(20) BYTE i,count
count=Contains(text,sub,positions)
IF count>0 THEN
PrintF("""%S"" contains %B ""%S"" at positions:",text,count,sub)
FOR i=0 TO count-1
DO
PrintB(positions(i))
IF i<count-1 THEN
Print(", ")
ELSE
PrintE(".")
FI
OD
ELSE
PrintF("""%S"" does not contain ""%S"".%E",text,sub)
FI
RETURN
PROC Main()
TestStartsWith("1234abc","123")
TestStartsWith("1234abc","234")
PutE()
TestContains("abbaabab","ab")
TestContains("abbaabab","ba")
TestContains("abbaabab","xyz")
PutE()
TestEndsWith("1234abc","abc")
TestEndsWith("1234abc","ab")
RETURN</lang>
- Output:
Screenshot from Atari 8-bit computer
"1234abc" starts with "123". "1234abc" does not start with "234". "abbaabab" contains 3 "ab" at positions:1, 5, 7. "abbaabab" contains 2 "ba" at positions:3, 6. "abbaabab" does not contain "xyz". "1234abc" ends with "abc". "1234abc" does not end with "ab".
Ada
<lang Ada> with Ada.Strings.Fixed; use Ada.Strings.Fixed; with Ada.Text_IO; use Ada.Text_IO;
procedure Match_Strings is
S1 : constant String := "abcd"; S2 : constant String := "abab"; S3 : constant String := "ab";
begin
if S1'Length >= S3'Length and then S1 (S1'First..S1'First + S3'Length - 1) = S3 then
Put_Line ( & S1 & "' starts with '" & S3 & );
end if;
if S2'Length >= S3'Length and then S2 (S2'Last - S3'Length + 1..S2'Last) = S3 then
Put_Line ( & S2 & "' ends with '" & S3 & );
end if;
Put_Line ( & S3 & "' first appears in '" & S1 & "' at" & Integer'Image (Index (S1, S3)));
Put_Line
( & S3 & "' appears in '" & S2 & &
Integer'Image (Ada.Strings.Fixed.Count (S2, S3)) & " times"
);
end Match_Strings; </lang>
- Output:
'abcd' starts with 'ab' 'abab' ends with 'ab' 'ab' first appears in 'abcd' at 1 'ab' appears in 'abab' 2 times
Aime
<lang aime>text t; data b;
b = "Bangkok";
t = "Bang";
o_form("starts with, embeds, ends with \"~\": ~, ~, ~\n", t, b.seek(t) == 0,
b.seek(t) != -1,
b.seek(t) != -1 && b.seek(t) + ~t == ~b);
t = "ok";
o_form("starts with, embeds, ends with \"~\": ~, ~, ~\n", t, b.seek(t) == 0,
b.seek(t) != -1,
b.seek(t) != -1 && b.seek(t) + ~t == ~b);
t = "Summer";
o_form("starts with, embeds, ends with \"~\": ~, ~, ~\n", t, b.seek(t) == 0,
b.seek(t) != -1,
b.seek(t) != -1 && b.seek(t) + ~t == ~b);</lang>
- Output:
starts with, embeds, ends with "Bang": 1, 1, 0 starts with, embeds, ends with "ok": 0, 1, 1 starts with, embeds, ends with "Summer": 0, 0, 0
ALGOL 68
<lang algol68># define some appropriate OPerators # PRIO STARTSWITH = 5, ENDSWITH = 5; OP STARTSWITH = (STRING str, prefix)BOOL: # assuming LWB = 1 #
IF UPB str < UPB prefix THEN FALSE ELSE str[:UPB prefix]=prefix FI;
OP ENDSWITH = (STRING str, suffix)BOOL: # assuming LWB = 1 #
IF UPB str < UPB suffix THEN FALSE ELSE str[UPB str-UPB suffix+1:]=suffix FI;
INT loc, loc2;
print((
"abcd" STARTSWITH "ab", # returns TRUE #
"abcd" ENDSWITH "zn", # returns FALSE #
string in string("bb",loc,"abab"), # returns FALSE #
string in string("ab",loc,"abab"), # returns TRUE #
(string in string("bb",loc,"abab")|loc|-1), # returns -1 #
(string in string("ab",loc,"abab")|loc|-1), # returns +1 #
(string in string("ab",loc2,"abab"[loc+1:])|loc+loc2|-1) # returns +3 #
))</lang>
- Output:
TFFT -1 +1 +3
AppleScript
<lang AppleScript>set stringA to "I felt happy because I saw the others were happy and because I knew I should feel happy, but I wasn’t really happy."
set string1 to "I felt happy" set string2 to "I should feel happy" set string3 to "I wasn't really happy"
-- Determining if the first string starts with second string stringA starts with string1 --> true
-- Determining if the first string contains the second string at any location stringA contains string2 --> true
-- Determining if the first string ends with the second string stringA ends with string3 --> false
-- Print the location of the match for part 2 offset of string2 in stringA --> 69</lang> AppleScript doesn't have a builtin means of matching multiple occurrences of a substring, however one can redefine the existing offset command to add this functionality: <lang AppleScript>-- Handle multiple occurrences of a string for part 2 on offset of needle in haystack local needle, haystack
if the needle is not in the haystack then return {} set my text item delimiters to the needle script property N : needle's length property t : {1 - N} & haystack's text items end script
tell the result repeat with i from 2 to (its t's length) - 1 set x to item i of its t set y to item (i - 1) of its t set item i of its t to (its N) + (x's length) + y end repeat
items 2 thru -2 of its t end tell end offset
offset of "happy" in stringA --> {8, 44, 83, 110}</lang>
or, defining an offsets function in terms of a more general findIndices:
<lang applescript>-- offsets :: String -> String -> [Int]
on offsets(needle, haystack)
script match
property mx : length of haystack
property d : (length of needle) - 1
on |λ|(x, i, xs)
set z to d + i
mx ≥ z and needle = text i thru z of xs
end |λ|
end script
findIndices(match, haystack)
end offsets
-- TEST ---------------------------------------------------
on run
set txt to "I felt happy because I saw the others " & ¬
"were happy and because I knew I should " & ¬
"feel happy, but I wasn’t really happy."
offsets("happy", txt)
--> {8, 44, 83, 110}
end run
-- GENERIC -------------------------------------------------
-- concatMap :: (a -> [b]) -> [a] -> [b] on concatMap(f, xs)
set lng to length of xs
set acc to {}
tell mReturn(f)
repeat with i from 1 to lng
set acc to acc & (|λ|(item i of xs, i, xs))
end repeat
end tell
return acc
end concatMap
-- findIndices :: (a -> Bool) -> [a] -> [Int]
-- findIndices :: (String -> Bool) -> String -> [Int]
on findIndices(p, xs)
script go
property f : mReturn(p)
on |λ|(x, i, xs)
if f's |λ|(x, i, xs) then
{i}
else
{}
end if
end |λ|
end script
concatMap(go, xs)
end findIndices
-- Lift 2nd class handler function into 1st class script wrapper
-- mReturn :: First-class m => (a -> b) -> m (a -> b)
on mReturn(f)
if script is class of f then
f
else
script
property |λ| : f
end script
end if
end mReturn</lang>
- Output:
{8, 44, 83, 110}
ARM Assembly
<lang ARM Assembly> /* ARM assembly Raspberry PI */ /* program strMatching.s */
/* Constantes */ .equ STDOUT, 1 @ Linux output console .equ EXIT, 1 @ Linux syscall .equ WRITE, 4 @ Linux syscall
/* Initialized data */ .data szMessFound: .asciz "String found. \n" szMessNotFound: .asciz "String not found. \n" szString: .asciz "abcdefghijklmnopqrstuvwxyz" szString2: .asciz "abc" szStringStart: .asciz "abcd" szStringEnd: .asciz "xyz" szStringStart2: .asciz "abcd" szStringEnd2: .asciz "xabc" szCarriageReturn: .asciz "\n"
/* UnInitialized data */ .bss
/* code section */ .text .global main main:
ldr r0,iAdrszString @ address input string ldr r1,iAdrszStringStart @ address search string
bl searchStringDeb @ Determining if the first string starts with second string cmp r0,#0 ble 1f ldr r0,iAdrszMessFound @ display message bl affichageMess b 2f
1:
ldr r0,iAdrszMessNotFound bl affichageMess
2:
ldr r0,iAdrszString @ address input string ldr r1,iAdrszStringEnd @ address search string bl searchStringFin @ Determining if the first string ends with the second string cmp r0,#0 ble 3f ldr r0,iAdrszMessFound @ display message bl affichageMess b 4f
3:
ldr r0,iAdrszMessNotFound bl affichageMess
4:
ldr r0,iAdrszString2 @ address input string ldr r1,iAdrszStringStart2 @ address search string
bl searchStringDeb @ cmp r0,#0 ble 5f ldr r0,iAdrszMessFound @ display message bl affichageMess b 6f
5:
ldr r0,iAdrszMessNotFound bl affichageMess
6:
ldr r0,iAdrszString2 @ address input string ldr r1,iAdrszStringEnd2 @ address search string bl searchStringFin cmp r0,#0 ble 7f ldr r0,iAdrszMessFound @ display message bl affichageMess b 8f
7:
ldr r0,iAdrszMessNotFound bl affichageMess
8:
ldr r0,iAdrszString @ address input string ldr r1,iAdrszStringEnd @ address search string bl searchSubString @ Determining if the first string contains the second string at any location cmp r0,#0 ble 9f ldr r0,iAdrszMessFound @ display message bl affichageMess b 10f
9:
ldr r0,iAdrszMessNotFound @ display substring result bl affichageMess
10:
100: @ standard end of the program
mov r0, #0 @ return code mov r7, #EXIT @ request to exit program svc 0 @ perform system call
iAdrszMessFound: .int szMessFound iAdrszMessNotFound: .int szMessNotFound iAdrszString: .int szString iAdrszString2: .int szString2 iAdrszStringStart: .int szStringStart iAdrszStringEnd: .int szStringEnd iAdrszStringStart2: .int szStringStart2 iAdrszStringEnd2: .int szStringEnd2 iAdrszCarriageReturn: .int szCarriageReturn /******************************************************************/ /* search substring at begin of input string */ /******************************************************************/ /* r0 contains the address of the input string */ /* r1 contains the address of substring */ /* r0 returns 1 if find or 0 if not or -1 if error */ searchStringDeb:
push {r1-r4,lr} @ save registers
mov r3,#0 @ counter byte string
ldrb r4,[r1,r3] @ load first byte of substring
cmp r4,#0 @ empty string ?
moveq r0,#-1 @ error
beq 100f
1:
ldrb r2,[r0,r3] @ load byte string input cmp r2,#0 @ zero final ? moveq r0,#0 @ not find beq 100f cmp r4,r2 @ bytes equals ? movne r0,#0 @ no not find bne 100f add r3,#1 @ increment counter ldrb r4,[r1,r3] @ and load next byte of substring cmp r4,#0 @ zero final ? bne 1b @ no -> loop mov r0,#1 @ yes is ok
100:
pop {r1-r4,lr} @ restaur registers
bx lr @ return
/******************************************************************/ /* search substring at end of input string */ /******************************************************************/ /* r0 contains the address of the input string */ /* r1 contains the address of substring */ /* r0 returns 1 if find or 0 if not or -1 if error */ searchStringFin:
push {r1-r5,lr} @ save registers
mov r3,#0 @ counter byte string
@ search the last character of substring
1:
ldrb r4,[r1,r3] @ load byte of substring
cmp r4,#0 @ zero final ?
addne r3,#1 @ no increment counter
bne 1b @ and loop
cmp r3,#0 @ empty string ?
moveq r0,#-1 @ error
beq 100f
sub r3,#1 @ index of last byte
ldrb r4,[r1,r3] @ load last byte of substring
@ search the last character of string
mov r2,#0 @ index last character
2:
ldrb r5,[r0,r2] @ load first byte of substring cmp r5,#0 @ zero final ? addne r2,#1 @ no -> increment counter bne 2b @ and loop cmp r2,#0 @ empty input string ? moveq r0,#0 @ yes -> not found beq 100f sub r2,#1 @ index last character
3:
ldrb r5,[r0,r2] @ load byte string input cmp r4,r5 @ bytes equals ? movne r0,#0 @ no -> not found bne 100f subs r3,#1 @ decrement counter movlt r0,#1 @ if zero -> ok found blt 100f subs r2,#1 @ decrement counter input string movlt r0,#0 @ if zero -> not found blt 100f ldrb r4,[r1,r3] @ load previous byte of substring b 3b @ and loop
100:
pop {r1-r5,lr} @ restaur registers
bx lr @ return
/******************************************************************/ /* search a substring in the string */ /******************************************************************/ /* r0 contains the address of the input string */ /* r1 contains the address of substring */ /* r0 returns index of substring in string or -1 if not found */ searchSubString:
push {r1-r6,lr} @ save registers
mov r2,#0 @ counter byte input string
mov r3,#0 @ counter byte string
mov r6,#-1 @ index found
ldrb r4,[r1,r3]
1:
ldrb r5,[r0,r2] @ load byte string cmp r5,#0 @ zero final ? moveq r0,#-1 @ yes returns error beq 100f cmp r5,r4 @ compare character beq 2f mov r6,#-1 @ no equals - > raz index mov r3,#0 @ and raz counter byte add r2,#1 @ and increment counter byte b 1b @ and loop
2: @ characters equals
cmp r6,#-1 @ first characters equals ? moveq r6,r2 @ yes -> index begin in r6 add r3,#1 @ increment counter substring ldrb r4,[r1,r3] @ and load next byte cmp r4,#0 @ zero final ? beq 3f @ yes -> end search add r2,#1 @ else increment counter string b 1b @ and loop
3:
mov r0,r6
100:
pop {r1-r6,lr} @ restaur registers
bx lr
/******************************************************************/ /* display text with size calculation */ /******************************************************************/ /* r0 contains the address of the message */ affichageMess:
push {r0,r1,r2,r7,lr} @ save registers
mov r2,#0 @ counter length */
1: @ loop length calculation
ldrb r1,[r0,r2] @ read octet start position + index
cmp r1,#0 @ if 0 its over
addne r2,r2,#1 @ else add 1 in the length
bne 1b @ and loop
@ so here r2 contains the length of the message
mov r1,r0 @ address message in r1
mov r0,#STDOUT @ code to write to the standard output Linux
mov r7, #WRITE @ code call system "write"
svc #0 @ call system
pop {r0,r1,r2,r7,lr} @ restaur registers
bx lr @ return
</lang>
Arturo
<lang rebol>print prefix? "abcd" "ab" print prefix? "abcd" "cd" print suffix? "abcd" "ab" print suffix? "abcd" "cd"
print contains? "abcd" "ab" print contains? "abcd" "xy"
print in? "ab" "abcd" print in? "xy" "abcd"
print index "abcd" "bc" print index "abcd" "xy"</lang>
- Output:
true false false true true false true false 1 null
AutoHotkey
<lang AutoHotkey> String1 = abcd String2 = abab
If (SubStr(String1,1,StrLen(String2)) = String2)
MsgBox, "%String1%" starts with "%String2%".
IfInString, String1, %String2% {
Position := InStr(String1,String2) StringReplace, String1, String1, %String2%, %String2%, UseErrorLevel MsgBox, "%String1%" contains "%String2%" at position %Position%`, and appears %ErrorLevel% times.
} StringRight, TempVar, String1, StrLen(String2) If TempVar = %String2%
MsgBox, "%String1%" ends with "%String2%".
</lang>
AutoIt
<lang AutoIt>$string1 = "arduinoardblobard" $string2 = "ard"
- == Determining if the first string starts with second string
If StringLeft($string1, StringLen($string2)) = $string2 Then ConsoleWrite("1st string starts with 2nd string." & @CRLF) Else ConsoleWrite("1st string does'nt starts with 2nd string." & @CRLF) EndIf
- == Determining if the first string contains the second string at any location
- == Print the location of the match for part 2
- == Handle multiple occurrences of a string for part 2
$start = 1 $count = 0 $pos = StringInStr($string1, $string2) While $pos $count += 1 ConsoleWrite("1st string contains 2nd string at position: " & $pos & @CRLF) $pos = StringInStr($string1, $string2, 0, 1, $start + $pos + StringLen($string2)) WEnd If $count = 0 Then ConsoleWrite("1st string does'nt contain 2nd string." & @CRLF)
- == Determining if the first string ends with the second string
If StringRight($string1, StringLen($string2)) = $string2 Then ConsoleWrite("1st string ends with 2nd string." & @CRLF) Else ConsoleWrite("1st string does'nt ends with 2nd string." & @CRLF) EndIf
</lang>
AWK
<lang AWK>#!/usr/bin/awk -f {
if ($1 ~ "^"$2) {
print $1" begins with "$2;
} else {
print $1" does not begin with "$2;
}
if ($1 ~ $2) {
print $1" contains "$2;
} else {
print $1" does not contain "$2;
}
if ($1 ~ $2"$") {
print $1" ends with "$2;
} else {
print $1" does not end with "$2;
}
} </lang>
BASIC
<lang qbasic>first$ = "qwertyuiop"
'Determining if the first string starts with second string second$ = "qwerty" IF LEFT$(first$, LEN(second$)) = second$ THEN
PRINT "'"; first$; "' starts with '"; second$; "'"
ELSE
PRINT "'"; first$; "' does not start with '"; second$; "'"
END IF
'Determining if the first string contains the second string at any location 'Print the location of the match for part 2 second$ = "wert" x = INSTR(first$, second$) IF x THEN
PRINT "'"; first$; "' contains '"; second$; "' at position "; x
ELSE
PRINT "'"; first$; "' does not contain '"; second$; "'"
END IF
' Determining if the first string ends with the second string second$ = "random garbage" IF RIGHT$(first$, LEN(second$)) = second$ THEN
PRINT "'"; first$; "' ends with '"; second$; "'"
ELSE
PRINT "'"; first$; "' does not end with '"; second$; "'"
END IF
</lang>
- Output:
'qwertyuiop' starts with 'qwerty' 'qwertyuiop' contains 'wert' at position 2 'qwertyuiop' does not end with 'random garbage'
Applesoft BASIC
<lang ApplesoftBasic>10 A$ = "THIS, THAT, AND THE OTHER THING" 20 S$ = "TH" 30 DEF FN S(P) = MID$(A$, P, LEN(S$)) = S$ 40 PRINT A$ : PRINT
110 S$(1) = "STARTS" 120 S$(0) = "DOES NOT START" 130 PRINT S$(FN S(1))" WITH "S$ : PRINT
210 R$ = "" : FOR I = 1 TO LEN(A$) - LEN(S$) : IF FN S(I) THEN R$ = R$ + STR$(I) + " " 220 NEXT I 230 IF LEN(R$) = 0 THEN PRINT "DOES NOT CONTAIN "S$ 240 IF LEN(R$) THEN PRINT "CONTAINS "S$" LOCATED AT POSITION "R$ 250 PRINT
310 E$(1) = "ENDS" 320 E$(0) = "DOES NOT END" 330 PRINT E$(FN S(LEN(A$) - LEN(S$) + 1))" WITH "S$</lang>
Batch File
<lang dos>::NOTE #1: This implementation might crash, or might not work properly if
- you put some of the CMD special characters (ex. %,!, etc) inside the strings.
- NOTE #2: The comparisons here are case-SENSITIVE.
- NOTE #3: Spaces in strings are considered.
@echo off setlocal enabledelayedexpansion
- The main things...
set "str1=qwertyuiop" set "str2=qwerty" call :str2_lngth call :matchbegin
set "str1=qweiuoiocghiioyiocxiisfguiioiuygvd" set "str2=io" call :str2_lngth call :matchcontain
set "str1=blablabla" set "str2=bbla" call :str2_lngth call :matchend
echo. pause exit /b 0
- /The main things.
- The functions...
- matchbegin
echo. if "!str1:~0,%length%!"=="!str2!" ( echo "%str1%" begins with "%str2%". ) else ( echo "%str1%" does not begin with "%str2%". ) goto :EOF
- matchcontain
echo. set curr=0&set exist=0
- scanchrloop
if "!str1:~%curr%,%length%!"=="" ( if !exist!==0 echo "%str1%" does not contain "%str2%". goto :EOF ) if "!str1:~%curr%,%length%!"=="!str2!" ( echo "%str1%" contains "%str2%". ^(in Position %curr%^) set exist=1 ) set /a curr+=1&goto scanchrloop
- matchend
echo. if "!str1:~-%length%!"=="!str2!" ( echo "%str1%" ends with "%str2%". ) else ( echo "%str1%" does not end with "%str2%". ) goto :EOF
- str2_lngth
set length=0
- loop
if "!str2:~%length%,1!"=="" goto :EOF set /a length+=1 goto loop
- /The functions.</lang>
- Output:
"qwertyuiop" begins with "qwerty". "qweiuoiocghiioyiocxiisfguiioiuygvd" contains "io". (in Position 6) "qweiuoiocghiioyiocxiisfguiioiuygvd" contains "io". (in Position 12) "qweiuoiocghiioyiocxiisfguiioiuygvd" contains "io". (in Position 15) "qweiuoiocghiioyiocxiisfguiioiuygvd" contains "io". (in Position 26) "blablabla" does not end with "bbla". Press any key to continue . . .
BBC BASIC
<lang bbcbasic> first$ = "The fox jumps over the dog"
FOR test% = 1 TO 3
READ second$
starts% = FN_first_starts_with_second(first$, second$)
IF starts% PRINT """" first$ """ starts with """ second$ """"
ends% = FN_first_ends_with_second(first$, second$)
IF ends% PRINT """" first$ """ ends with """ second$ """"
where% = FN_first_contains_second_where(first$, second$)
IF where% PRINT """" first$ """ contains """ second$ """ at position " ; where%
howmany% = FN_first_contains_second_howmany(first$, second$)
IF howmany% PRINT """" first$ """ contains """ second$ """ " ; howmany% " time(s)"
NEXT
DATA "The", "he", "dog"
END
DEF FN_first_starts_with_second(A$, B$)
= B$ = LEFT$(A$, LEN(B$))
DEF FN_first_ends_with_second(A$, B$)
= B$ = RIGHT$(A$, LEN(B$))
DEF FN_first_contains_second_where(A$, B$)
= INSTR(A$, B$)
DEF FN_first_contains_second_howmany(A$, B$)
LOCAL I%, N% : I% = 0
REPEAT
I% = INSTR(A$, B$, I%+1)
IF I% THEN N% += 1
UNTIL I% = 0
= N%
</lang>
- Output:
"The fox jumps over the dog" starts with "The" "The fox jumps over the dog" contains "The" at position 1 "The fox jumps over the dog" contains "The" 1 time(s) "The fox jumps over the dog" contains "he" at position 2 "The fox jumps over the dog" contains "he" 2 time(s) "The fox jumps over the dog" ends with "dog" "The fox jumps over the dog" contains "dog" at position 24 "The fox jumps over the dog" contains "dog" 1 time(s)
BQN
⍷ does much of the heavy lifting here. It is commuted with ˜ so the order of the arguments makes sense.
<lang bqn>SW ← ⊑⍷˜
⊑⍷˜
Contains ← ∨´⍷˜
∨´⍷˜
EW ← ¯1⊑⍷˜
¯1⊑⍷˜
Locs ← /⍷˜
/⍷˜
"abcd" SW "ab"
1
"abcd" SW "cd"
0
"abcd" EW "ab"
0
"abcd" EW "cd"
1
"abcd" Contains "bb"
0
"abcd" Contains "ab"
1
"abcd" Contains "bc"
1
"abab" Contains "ab"
1
"abab" Locs "ab"
⟨ 0 2 ⟩</lang>
Bracmat
Bracmat does pattern matching in expressions subject:pattern and in strings @(subject:pattern). The (sub)pattern ? is a wild card.
<lang Bracmat>( (sentence="I want a number such that that number will be even.")
& out$(@(!sentence:I ?) & "sentence starts with 'I'" | "sentence does not start with 'I'")
& out$(@(!sentence:? such ?) & "sentence contains 'such'" | "sentence does not contain 'such'")
& out$(@(!sentence:? "even.") & "sentence ends with 'even.'" | "sentence does not end with 'even.'")
& 0:?N
& ( @(!sentence:? be (? & !N+1:?N & ~))
| out$str$("sentence contains " !N " occurrences of 'be'")
)
)</lang>
In the last line, Bracmat is forced by the always failing node ~ to backtrack until all occurrences of 'be' are found.
Thereafter the pattern match expression fails.
The interesting part is the side effect: while backtracking,
the accumulator N keeps track of how many are found.
- Output:
sentence starts with 'I' sentence contains 'such' sentence ends with 'even.' sentence contains 3 occurrences of 'be'
C
Case sensitive matching: <lang C>#include <string.h>
- include <stdio.h>
int startsWith(const char* container, const char* target) {
size_t clen = strlen(container), tlen = strlen(target); if (clen < tlen) return 0; return strncmp(container, target, tlen) == 0;
}
int endsWith(const char* container, const char* target) {
size_t clen = strlen(container), tlen = strlen(target); if (clen < tlen) return 0; return strncmp(container + clen - tlen, target, tlen) == 0;
}
int doesContain(const char* container, const char* target) {
return strstr(container, target) != 0;
}
int main(void) {
printf("Starts with Test ( Hello,Hell ) : %d\n", startsWith("Hello","Hell"));
printf("Ends with Test ( Code,ode ) : %d\n", endsWith("Code","ode"));
printf("Contains Test ( Google,msn ) : %d\n", doesContain("Google","msn"));
return 0;
}</lang>
- Output:
Starts with Test ( Hello,Hell ) : 1 Ends with Test ( Code,ode ) : 1 Contains Test ( Google,msn ) : 0
Code without using string library to demonstrate how char strings are just pointers: <lang C>#include <stdio.h>
/* returns 0 if no match, 1 if matched, -1 if matched and at end */ int s_cmp(const char *a, const char *b) {
char c1 = 0, c2 = 0;
while (c1 == c2) {
c1 = *(a++);
if ('\0' == (c2 = *(b++)))
return c1 == '\0' ? -1 : 1;
}
return 0;
}
/* returns times matched */ int s_match(const char *a, const char *b) {
int i = 0, count = 0;
printf("matching `%s' with `%s':\n", a, b);
while (a[i] != '\0') {
switch (s_cmp(a + i, b)) {
case -1:
printf("matched: pos %d (at end)\n\n", i);
return ++count;
case 1:
printf("matched: pos %d\n", i);
++count;
break;
}
i++;
}
printf("end match\n\n");
return count;
}
int main() {
s_match("A Short String", "ort S");
s_match("aBaBaBaBa", "aBa");
s_match("something random", "Rand");
return 0;
}</lang>
- Output:
matching `A Short String' with `ort S': matched: pos 4 end match matching `aBaBaBaBa' with `aBa': matched: pos 0 matched: pos 2 matched: pos 4 matched: pos 6 (at end) matching `something random' with `Rand': end match
C#
<lang csharp> class Program { public static void Main (string[] args) { var value = "abcd".StartsWith("ab"); value = "abcd".EndsWith("zn"); //returns false value = "abab".Contains("bb"); //returns false value = "abab".Contains("ab"); //returns true int loc = "abab".IndexOf("bb"); //returns -1 loc = "abab".IndexOf("ab"); //returns 0 loc = "abab".IndexOf("ab",loc+1); //returns 2 } } </lang>
C++
<lang cpp>#include <string> using namespace std;
string s1="abcd"; string s2="abab"; string s3="ab"; //Beginning s1.compare(0,s3.size(),s3)==0; //End s1.compare(s1.size()-s3.size(),s3.size(),s3)==0; //Anywhere s1.find(s2)//returns string::npos int loc=s2.find(s3)//returns 0 loc=s2.find(s3,loc+1)//returns 2</lang>
Clojure
<lang clojure>(def evals '((. "abcd" startsWith "ab") (. "abcd" endsWith "zn") (. "abab" contains "bb") (. "abab" contains "ab") (. "abab" indexOf "bb") (let [loc (. "abab" indexOf "ab")] (. "abab" indexOf "ab" (dec loc)))))
user> (for [i evals] [i (eval i)]) ([(. "abcd" startsWith "ab") true] [(. "abcd" endsWith "zn") false] [(. "abab" contains "bb") false] [(. "abab" contains "ab") true] [(. "abab" indexOf "bb") -1] [(let [loc (. "abab" indexOf "ab")] (. "abab" indexOf "ab" (dec loc))) 0])</lang>
CoffeeScript
This example uses string slices, but a better implementation might use indexOf for slightly better performance.
<lang coffeescript> matchAt = (s, frag, i) ->
s[i...i+frag.length] == frag
startsWith = (s, frag) ->
matchAt s, frag, 0
endsWith = (s, frag) ->
matchAt s, frag, s.length - frag.length
matchLocations = (s, frag) ->
(i for i in [0..s.length - frag.length] when matchAt s, frag, i)
console.log startsWith "tacoloco", "taco" # true console.log startsWith "taco", "tacoloco" # false console.log startsWith "tacoloco", "talk" # false console.log endsWith "tacoloco", "loco" # true console.log endsWith "loco", "tacoloco" # false console.log endsWith "tacoloco", "yoco" # false console.log matchLocations "bababab", "bab" # [0,2,4] console.log matchLocations "xxx", "x" # [0,1,2] </lang>
Common Lisp
<lang lisp> (defun starts-with-p (str1 str2)
"Determine whether `str1` starts with `str2`" (let ((p (search str2 str1))) (and p (= 0 p))))
(print (starts-with-p "foobar" "foo")) ; T (print (starts-with-p "foobar" "bar")) ; NIL
(defun ends-with-p (str1 str2)
"Determine whether `str1` ends with `str2`" (let ((p (mismatch str2 str1 :from-end T))) (or (not p) (= 0 p))))
(print (ends-with-p "foobar" "foo")) ; NIL (print (ends-with-p "foobar" "bar")) ; T
(defun containsp (str1 str2)
"Determine whether `str1` contains `str2`.
Instead of just returning T, return a list of starting locations
for every occurence of `str2` in `str1`"
(unless (string-equal str2 "")
(loop for p = (search str2 str1) then (search str2 str1 :start2 (1+ p))
while p
collect p)))
(print (containsp "foobar" "oba")) ; (2) (print (containsp "ababaBa" "ba")) ; (1 3) (print (containsp "foobar" "x")) ; NIL </lang>
Component Pascal
BlackBox Component Builder <lang oberon2> MODULE StringMatch; IMPORT StdLog,Strings; CONST strSize = 1024; patSize = 256;
TYPE Matcher* = POINTER TO LIMITED RECORD str: ARRAY strSize OF CHAR; pat: ARRAY patSize OF CHAR; pos: INTEGER END;
PROCEDURE NewMatcher*(IN str: ARRAY OF CHAR): Matcher; VAR m: Matcher; BEGIN NEW(m);m.str := str$;m.pos:= 0; RETURN m END NewMatcher;
PROCEDURE (m: Matcher) Match*(IN pat: ARRAY OF CHAR): INTEGER,NEW; VAR pos: INTEGER; BEGIN m.pat := pat$; pos := m.pos; Strings.Find(m.str,m.pat,pos,m.pos); RETURN m.pos END Match;
PROCEDURE (m: Matcher) Next*(): INTEGER, NEW; VAR pos: INTEGER; BEGIN pos := m.pos + LEN(m.pat$); Strings.Find(m.str,m.pat,pos,m.pos); RETURN m.pos; END Next;
(* Some Helper functions based on Strings module *) PROCEDURE StartsWith(IN str: ARRAY OF CHAR;IN pat: ARRAY OF CHAR): BOOLEAN; VAR pos: INTEGER; BEGIN Strings.Find(str,pat,0,pos); RETURN pos = 0 END StartsWith;
PROCEDURE Contains(IN str: ARRAY OF CHAR;IN pat: ARRAY OF CHAR; OUT pos: INTEGER): BOOLEAN; BEGIN Strings.Find(str,pat,0,pos); RETURN pos >= 0 END Contains;
PROCEDURE EndsWith(IN str: ARRAY OF CHAR;IN pat: ARRAY OF CHAR): BOOLEAN; VAR pos: INTEGER; BEGIN Strings.Find(str,pat,0,pos); RETURN pos + LEN(pat$) = LEN(str$) END EndsWith;
PROCEDURE Do*; CONST aStr = "abcdefghijklmnopqrstuvwxyz"; VAR pat: ARRAY 128 OF CHAR; res: BOOLEAN; at: INTEGER; m: Matcher; BEGIN (* StartsWith *) pat := "abc"; StdLog.String(aStr + " startsWith " + pat + " :>");StdLog.Bool(StartsWith(aStr,pat));StdLog.Ln; pat := "cba"; StdLog.String(aStr + " startsWith " + pat + " :>");StdLog.Bool(StartsWith(aStr,pat));StdLog.Ln; pat := "def"; StdLog.String(aStr + " startsWith " + pat + " :>");StdLog.Bool(StartsWith(aStr,pat));StdLog.Ln; StdLog.Ln; (* Contains *) pat := 'def'; StdLog.String(aStr + " contains " + pat + " :>");StdLog.Bool(Contains(aStr,pat,at)); StdLog.String(" at: ");StdLog.Int(at);StdLog.Ln; pat := 'efd'; StdLog.String(aStr + " contains " + pat + " :>");StdLog.Bool(Contains(aStr,pat,at)); StdLog.String(" at: ");StdLog.Int(at);StdLog.Ln; pat := 'abc'; StdLog.String(aStr + " contains " + pat + " :>");StdLog.Bool(Contains(aStr,pat,at)); StdLog.String(" at: ");StdLog.Int(at);StdLog.Ln; pat := 'xyz'; StdLog.String(aStr + " contains " + pat + " :>");StdLog.Bool(Contains(aStr,pat,at)); StdLog.String(" at: ");StdLog.Int(at);StdLog.Ln; StdLog.Ln; (* EndsWith *) pat := 'xyz'; StdLog.String(aStr + " endsWith " + pat + " :>");StdLog.Bool(EndsWith(aStr,pat));StdLog.Ln; pat := 'zyx'; StdLog.String(aStr + " endsWith " + pat + " :>");StdLog.Bool(EndsWith(aStr,pat));StdLog.Ln; pat := 'abc'; StdLog.String(aStr + " endsWith " + pat + " :>");StdLog.Bool(EndsWith(aStr,pat));StdLog.Ln; pat:= 'def'; StdLog.String(aStr + " endsWith " + pat + " :>");StdLog.Bool(EndsWith(aStr,pat));StdLog.Ln; StdLog.Ln;
m := NewMatcher("abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz");
StdLog.String("Matching 'abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz' against 'abc':> ");
StdLog.Ln;
StdLog.String("Match at: ");StdLog.Int(m.Match("abc"));StdLog.Ln;
StdLog.String("Match at: ");StdLog.Int(m.Next());StdLog.Ln;
StdLog.String("Match at: ");StdLog.Int(m.Next());StdLog.Ln
END Do;
END StringMatch.
</lang>
Execute: ^Q StringMatching.Do
- Output:
abcdefghijklmnopqrstuvwxyz startsWith abc :> $TRUE abcdefghijklmnopqrstuvwxyz startsWith cba :> $FALSE abcdefghijklmnopqrstuvwxyz startsWith def :> $FALSE abcdefghijklmnopqrstuvwxyz contains def :> $TRUE at: 3 abcdefghijklmnopqrstuvwxyz contains efd :> $FALSE at: -1 abcdefghijklmnopqrstuvwxyz contains abc :> $TRUE at: 0 abcdefghijklmnopqrstuvwxyz contains xyz :> $TRUE at: 23 abcdefghijklmnopqrstuvwxyz endsWith xyz :> $TRUE abcdefghijklmnopqrstuvwxyz endsWith zyx :> $FALSE abcdefghijklmnopqrstuvwxyz endsWith abc :> $FALSE abcdefghijklmnopqrstuvwxyz endsWith def :> $FALSE Matching 'abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz' against 'abc':> Match at: 0 Match at: 26 Match at: -1
D
<lang d>void main() {
import std.stdio; import std.algorithm: startsWith, endsWith, find, countUntil;
"abcd".startsWith("ab").writeln; // true
"abcd".endsWith("zn").writeln; // false
"abab".find("bb").writeln; // empty array (no match)
"abcd".find("bc").writeln; // "bcd" (substring start
// at match)
"abab".countUntil("bb").writeln; // -1 (no match)
"abab".countUntil("ba").writeln; // 1 (index of 1st match)
// std.algorithm.startsWith also works on arrays and ranges: [1, 2, 3].countUntil(3).writeln; // 2 [1, 2, 3].countUntil([2, 3]).writeln; // 1
}</lang>
- Output:
true false bcd -1 1 2 1
DCL
<lang DCL>$ first_string = p1 $ length_of_first_string = f$length( first_string ) $ second_string = p2 $ length_of_second_string = f$length( second_string ) $ offset = f$locate( second_string, first_string ) $ if offset .eq. 0 $ then $ write sys$output "first string starts with second string" $ else $ write sys$output "first string does not start with second string" $ endif $ if offset .ne. length_of_first_string $ then $ write sys$output "first string contains the second string at location ", offset $ else $ write sys$output "first string does not contain the second string at any location" $ endif $ temp = f$extract( length_of_first_string - length_of_second_string, length_of_second_string, first_string ) $ if second_string .eqs. temp $ then $ write sys$output "first string ends with the second string" $ else $ write sys$output "first string does not end with the second string" $ endif</lang>
- Output:
$ @string_matching efabcdef ef first string starts with second string first string contains the second string at location 0 first string ends with the second string $ @string_matching efabcdef ab first string does not start with second string first string contains the second string at location 2 first string does not end with the second string $ @string_matching efabcdef def first string does not start with second string first string contains the second string at location 5 first string ends with the second string $ @string_matching efabcdef defx first string does not start with second string first string does not contain the second string at any location first string does not end with the second string
Delphi
<lang Delphi>program CharacterMatching;
{$APPTYPE CONSOLE}
uses StrUtils;
begin
WriteLn(AnsiStartsText('ab', 'abcd')); // True
WriteLn(AnsiEndsText('zn', 'abcd')); // False
WriteLn(AnsiContainsText('abcd', 'bb')); // False
Writeln(AnsiContainsText('abcd', 'ab')); // True
WriteLn(Pos('ab', 'abcd')); // 1
end.</lang>
Dyalect
<lang Dyalect>var value = "abcd".StartsWith("ab") value = "abcd".EndsWith("zn") //returns false value = "abab".Contains("bb") //returns false value = "abab".Contains("ab") //returns true var loc = "abab".IndexOf("bb") //returns -1 loc = "abab".IndexOf("ab") //returns 0</lang>
E
<lang e>def f(string1, string2) {
println(string1.startsWith(string2))
var index := 0
while ((index := string1.startOf(string2, index)) != -1) {
println(`at $index`)
index += 1
}
println(string1.endsWith(string2))
}</lang>
EchoLisp
<lang lisp> (string-suffix? "nette" "Antoinette") → #t (string-prefix? "Simon" "Simon & Garfunkel") → #t
(string-match "Antoinette" "net") → #t ;; contains (string-index "net" "Antoinette") → 5 ;; substring location </lang>
Elena
ELENA 4.x : <lang elena>import extensions;
public program() {
var s := "abcd"; console.printLine(s," starts with ab: ",s.startingWith:"ab"); console.printLine(s," starts with cd: ",s.startingWith:"cd"); console.printLine(s," ends with ab: ",s.endingWith:"ab"); console.printLine(s," ends with cd: ",s.endingWith:"cd"); console.printLine(s," contains ab: ",s.containing:"ab"); console.printLine(s," contains bc: ",s.containing:"bc"); console.printLine(s," contains cd: ",s.containing:"cd"); console.printLine(s," contains az: ",s.containing:"az"); console.printLine(s," index of az: ",s.indexOf(0, "az")); console.printLine(s," index of cd: ",s.indexOf(0, "cd")); console.printLine(s," index of bc: ",s.indexOf(0, "bc")); console.printLine(s," index of ab: ",s.indexOf(0, "ab")); console.readChar()
}</lang>
Elixir
The String module has functions that cover the base requirements. <lang elixir>s1 = "abcd" s2 = "adab" s3 = "ab"
String.starts_with?(s1, s3)
- => true
String.starts_with?(s2, s3)
- => false
String.contains?(s1, s3)
- => true
String.contains?(s2, s3)
- => true
String.ends_with?(s1, s3)
- => false
String.ends_with?(s2, s3)
- => true
- Optional requirements:
Regex.run(~r/#{s3}/, s1, return: :index)
- => [{0, 2}]
Regex.run(~r/#{s3}/, s2, return: :index)
- => [{2, 2}]
Regex.scan(~r/#{s3}/, "abcabc", return: :index)
- => [[{0, 2}], [{3, 2}]]</lang>
Emacs Lisp
<lang Lisp>(defun string-contains (needle haystack)
(string-match (regexp-quote needle) haystack))
(string-prefix-p "before" "before center after") ;=> t (string-contains "before" "before center after") ;=> 0 (string-suffix-p "before" "before center after") ;=> nil
(string-prefix-p "center" "before center after") ;=> nil (string-contains "center" "before center after") ;=> 7 (string-suffix-p "center" "before center after") ;=> nil
(string-prefix-p "after" "before center after") ;=> nil (string-contains "after" "before center after") ;=> 14 (string-suffix-p "after" "before center after") ;=> t</lang>
Erlang
<lang erlang> -module(character_matching). -export([starts_with/2,ends_with/2,contains/2]).
%% Both starts_with and ends_with are mappings to 'lists:prefix/2' and %% 'lists:suffix/2', respectively.
starts_with(S1,S2) ->
lists:prefix(S2,S1).
ends_with(S1,S2) ->
lists:suffix(S2,S1).
contains(S1,S2) ->
contains(S1,S2,1,[]).
%% While S1 is at least as long as S2 we check if S2 is its prefix, %% storing the result if it is. When S1 is shorter than S2, we return %% the result. NB: this will work on any arbitrary list in erlang %% since it makes no distinction between strings and lists. contains([_|T]=S1,S2,N,Acc) when length(S2) =< length(S1) ->
case starts_with(S1,S2) of
true ->
contains(T,S2,N+1,[N|Acc]);
false ->
contains(T,S2,N+1,Acc)
end;
contains(_S1,_S2,_N,Acc) ->
Acc.
</lang>
Euphoria
<lang euphoria>sequence first, second integer x
first = "qwertyuiop"
-- Determining if the first string starts with second string second = "qwerty" if match(second, first) = 1 then
printf(1, "'%s' starts with '%s'\n", {first, second})
else
printf(1, "'%s' does not start with '%s'\n", {first, second})
end if
-- Determining if the first string contains the second string at any location -- Print the location of the match for part 2 second = "wert" x = match(second, first) if x then
printf(1, "'%s' contains '%s' at position %d\n", {first, second, x})
else
printf(1, "'%s' does not contain '%s'\n", {first, second})
end if
-- Determining if the first string ends with the second string second = "uio" if length(second)<=length(first) and match_from(second, first, length(first)-length(second)+1) then
printf(1, "'%s' ends with '%s'\n", {first, second})
else
printf(1, "'%s' does not end with '%s'\n", {first, second})
end if</lang>
- Output:
'qwertyuiop' starts with 'qwerty' 'qwertyuiop' contains 'wert' at position 2 'qwertyuiop' does not end with 'uio'
F#
<lang fsharp>[<EntryPoint>] let main args =
let text = "一二三四五六七八九十" let starts = "一二" let ends = "九十" let contains = "五六" let notContains = "百"
printfn "text = %A" text
printfn "starts with %A: %A" starts (text.StartsWith(starts))
printfn "starts with %A: %A" ends (text.StartsWith(ends))
printfn "ends with %A: %A" ends (text.EndsWith(ends))
printfn "ends with %A: %A" starts (text.EndsWith(starts))
printfn "contains %A: %A" contains (text.Contains(contains))
printfn "contains %A: %A" notContains (text.Contains(notContains))
printfn "substring %A begins at position %d (zero-based)" contains (text.IndexOf(contains))
let text2 = text + text
printfn "text = %A" text2
Seq.unfold (fun (n : int) ->
let idx = text2.IndexOf(contains, n)
if idx < 0 then None else Some (idx, idx+1)) 0
|> Seq.iter (printfn "substring %A begins at position %d (zero-based)" contains)
0</lang>
- Output:
text = "一二三四五六七八九十" starts with "一二": true starts with "九十": false ends with "九十": true ends with "一二": false contains "五六": true contains "百": false substring "五六" begins at position 4 (zero-based) text = "一二三四五六七八九十一二三四五六七八九十" substring "五六" begins at position 4 (zero-based) substring "五六" begins at position 14 (zero-based)
Factor
Does cheesecake start with cheese?
<lang factor>"cheesecake" "cheese" head? ! t</lang>
Does cheesecake contain sec at any location?
<lang factor>"sec" "cheesecake" subseq? ! t</lang>
Does cheesecake end with cake?
<lang factor>"cheesecake" "cake" tail? ! t</lang>
Where in cheesecake is the leftmost sec?
<lang factor>"sec" "cheesecake" subseq-start ! 4</lang>
Where in Mississippi are all occurrences of iss?
<lang factor>USE: regexp
"Mississippi" "iss" <regexp> all-matching-slices [ from>> ] map ! { 1 4 }</lang>
Falcon
'VBA/Python programmer's approach. I'm just a junior Falconeer but this code seems falconic <lang falcon> /* created by Aykayayciti Earl Lamont Montgomery April 9th, 2018 */
s1 = "Naig Ialocin Olracnaig" s2 = "Naig"
var = s1.startsWith(s2) ? s1 + " starts with " + s2 : s1 + " does not start with " + s2 > var
s2 = "loc" var = s2 in s1 ? @ "$s1 contains $s2" : @ "$s1 does not contain $s2" > var
> s1.endsWith(s2) ? @ "s1 ends with $s2" : @ "$s1 does not end with $s2" </lang>
- Output:
Naig Ialocin Olracnaig starts with Naig Naig Ialocin Olracnaig contains loc Naig Ialocin Olracnaig does not end with loc [Finished in 1.2s]
Fantom
Fantom provides several self-explanatory string-matching methods:
startsWithendsWithcontainsindex(takes an optional index, for the start position)indexIgnoreCase(like above, ignoring case for ASCII characters)indexr(start search from end of string, with an optional index)indexrIgnoreCase(like above, ignoring case for ASCII characters)
<lang fantom> class Main {
public static Void main ()
{
string := "Fantom Language"
echo ("String is: " + string)
echo ("does string start with 'Fantom'? " + string.startsWith("Fantom"))
echo ("does string start with 'Language'? " + string.startsWith("Language"))
echo ("does string contain 'age'? " + string.contains("age"))
echo ("does string contain 'page'? " + string.contains("page"))
echo ("does string end with 'Fantom'? " + string.endsWith("Fantom"))
echo ("does string end with 'Language'? " + string.endsWith("Language"))
echo ("Location of 'age' is: " + string.index("age"))
posn := string.index ("an")
echo ("First location of 'an' is: " + posn)
posn = string.index ("an", posn+1)
echo ("Second location of 'an' is: " + posn)
posn = string.index ("an", posn+1)
if (posn == null) echo ("No third location of 'an'")
}
} </lang>
- Output:
String is: Fantom Language does string start with 'Fantom'? true does string start with 'Language'? false does string contain 'age'? true does string contain 'page'? false does string end with 'Fantom'? false does string end with 'Language'? true Location of 'age' is: 12 First location of 'an' is: 1 Second location of 'an' is: 8 No third location of 'an'
FBSL
<lang qbasic>#APPTYPE CONSOLE
DIM s = "roko, mat jane do"
IF LEFT(s, 4) = "roko" THEN PRINT STRENC(s), " starts with ", STRENC("roko") IF INSTR(s, "mat") THEN PRINT STRENC(s), " contains ", STRENC("mat"), " at ", INSTR IF RIGHT(s, 2) = "do" THEN PRINT STRENC(s), " ends with ", STRENC("do") PRINT STRENC(s), " contains ", STRENC("o"), " at the following locations:", InstrEx(s, "o")
PAUSE
SUB InstrEx(mane, match)
INSTR = 0 WHILE INSTR(mane, match, INSTR + 1): PRINT " ", INSTR;: WEND
END SUB </lang>
- Output:
"roko, mat jane do" starts with "roko" "roko, mat jane do" contains "mat" at 7 "roko, mat jane do" ends with "do" "roko, mat jane do" contains "o" at the following locations: 2 4 17 Press any key to continue...
Forth
<lang forth>: starts-with ( a l a2 l2 -- ? )
tuck 2>r min 2r> compare 0= ;
- ends-with ( a l a2 l2 -- ? )
tuck 2>r negate over + 0 max /string 2r> compare 0= ;
\ use SEARCH ( a l a2 l2 -- a3 l3 ? ) for contains</lang>
Fortran
Fortran does not offer a string type, but since F77 it has been possible to use a CHARACTER variable, of some specified size, whose size may be accessed via the LEN function. When passed as a parameter, a secret additional parameter specifies its size and so string-like usage is possible. Character matching is case sensitive, and, trailing spaces are ignored so that "xx" and "xx " are deemed equal. The function INDEX(text,target) determines the first index in text where target matches, and returns zero if there is no such match. Unfortunately, the function does not allow the specification of a starting position for a search, as to find any second and further matches. One must specify something like INDEX(text(5:),target) to start with position five, and then deal with the resulting offsets needed to relate the result to positions within the parameter. On the other hand, since there is no "length" conjoined to the text such substring selections can be made without copying the text to a work area, unlike the copy(text,start,stop) equivalent of Pascal for example. Some Fortran compilers do offer a starting point, and also an option to search backwards from the end, but these facilities are not guaranteed. Similarly, INDEX is only made available for CHARACTER searching, even though it could easily be generalised to other types.
A second problem is presented by the possibility that a logical expression such as L.LT.0 .OR. etc. will always or might possibly or in certain constructions but not others be fully evaluated, which is to say that the etc will be evaluated even though L < 0 is true so that the result is determined. And in this case, evaluating the etc will cause trouble because the indexing won't work! To be safe, therefore, a rather lame two-stage test is required - though optimising compilers might well shift code around anyway.
In the case of STARTS, these annoyances can be left to the INDEX function rather than comparing the start of A against B. At the cost of it searching the whole of A if B is not at the start. Otherwise, it would be the mirror of ENDS.
<lang Fortran>
SUBROUTINE STARTS(A,B) !Text A starts with text B?
CHARACTER*(*) A,B
IF (INDEX(A,B).EQ.1) THEN !Searches A to find B.
WRITE (6,*) ">",A,"< starts with >",B,"<"
ELSE
WRITE (6,*) ">",A,"< does not start with >",B,"<"
END IF
END SUBROUTINE STARTS
SUBROUTINE HAS(A,B) !Text B appears somewhere in text A?
CHARACTER*(*) A,B
INTEGER L
L = INDEX(A,B) !The first position in A where B matches.
IF (L.LE.0) THEN
WRITE (6,*) ">",A,"< does not contain >",B,"<"
ELSE
WRITE (6,*) ">",A,"< contains a >",B,"<, offset",L
END IF
END SUBROUTINE HAS
SUBROUTINE ENDS(A,B) !Text A ends with text B.
CHARACTER*(*) A,B
INTEGER L
L = LEN(A) - LEN(B) !Find the tail end of A that B might match.
IF (L.LT.0) THEN !Dare not use an OR, because of full evaluation risks.
WRITE (6,*) ">",A,"< is too short to end with >",B,"<" !Might as well have a special message.
ELSE IF (A(L + 1:L + LEN(B)).NE.B) THEN !Otherwise, it is safe to look.
WRITE (6,*) ">",A,"< does not end with >",B,"<"
ELSE
WRITE (6,*) ">",A,"< ends with >",B,"<"
END IF
END SUBROUTINE ENDS
CALL STARTS("This","is")
CALL STARTS("Theory","The")
CALL HAS("Bananas","an")
CALL ENDS("Banana","an")
CALL ENDS("Banana","na")
CALL ENDS("Brief","Much longer")
END
</lang> Output: text strings are bounded by >etc.< in case of leading or trailing spaces.
>This< does not start with >is< >Theory< starts with >The< >Bananas< contains a >an<, offset 2 >Banana< does not end with >an< >Banana< ends with >na< >Brief< is too short to end with >Much longer<
Similar program using modern Fortran style <lang Fortran> !----------------------------------------------------------------------- !Main program string_matching !----------------------------------------------------------------------- program string_matching
implicit none
character(len=*), parameter :: fmt= '(I0)'
write(*,fmt) starts("this","is")
write(*,fmt) starts("theory","the")
write(*,fmt) has("bananas","an")
write(*,fmt) ends("banana","an")
write(*,fmt) ends("banana","na")
write(*,fmt) ends("brief","much longer")
contains
! Determining if the first string starts with second string
function starts(string1, string2) result(answer)
implicit none
character(len=*), intent(in) :: string1
character(len=*), intent(in) :: string2
integer :: answer
answer = 0
if(len(string2)>len(string1)) return
if(string1(1:len(string2))==string2) answer = 1
end function starts
! Determining if the first string contains the second string at any location
function has(string1, string2) result(answer)
implicit none
character(len=*), intent(in) :: string1
character(len=*), intent(in) :: string2
character(len=:),allocatable :: temp
integer :: answer, add
character(len=*), parameter :: fmt= '(A6,X,I0)'
answer = 0
add = 0
if(len(string2)>len(string1)) return
answer = index(string1, string2)
if(answer==0) return
! Print the location of the match for part 2
write(*,fmt) " at ", answer
! Handle multiple occurrences of a string for part 2.
add = answer
temp = string1(answer+1:)
do while(answer>0)
answer = index(temp, string2)
add = add + answer
if(answer>0) write(*,fmt) " at ", add
! deallocate(temp)
temp = string1(add+1:) ! auto reallocation
enddo
answer = 1
end function has
! Determining if the first string ends with the second string
function ends(string1, string2) result(answer)
implicit none
character(len=*), intent(in) :: string1
character(len=*), intent(in) :: string2
integer :: answer
answer = 0
if(len(string2)>len(string1)) return
if(string1(len(string1)-len(string2)+1:)==string2) answer = 1
end function ends
end program string_matching </lang> Output: false = 0, true = 1 ( + multiple occurrences if applicable)
0 1 at 2 at 4 1 0 1 0
In recent standards of Fortran strings as intrinsic first-class type and many intrinsic procedures for strings manipulation have been added.
FreeBASIC
<lang freebasic>' FB 1.05.0 Win64
Dim As String s1 = "abracadabra" Dim As String s2 = "abra" Print "First string : "; s1 Print "Second string : "; s2 Print Print "First string begins with second string : "; CBool(s2 = Left(s1, Len(s2))) Dim As Integer i1 = Instr(s1, s2) Dim As Integer i2 Print "First string contains second string : "; If i1 Then
Print "at index"; i1; i2 = Instr(i1 + Len(s2), s1, s2) If i2 Then Print " and at index"; i2 Else Print End If
Else
Print "false";
End If Print "First string ends with second string : "; CBool(s2 = Right(s1, Len(s2))) Print Print "Press any key to quit" Sleep</lang>
- Output:
First string : abracadabra Second string : abra First string begins with second string : true First string contains second string : at index 1 and at index 8 First string ends with second string : true
Gambas
Click this link to run this code <lang gambas>Public Sub Main() Dim sString1 As String = "Hello world" Dim sString2 As String = "Hello"
Print sString1 Begins Left(sString2, 5) 'Determine if the first string starts with second string If InStr(sString1, sString2) Then Print "True" Else Print "False" 'Determine if the first string contains the second string at any location Print sString1 Ends Left(sString2, 5) 'Determine if the first string ends with the second string
End</lang> Output:
True True False
GML
<lang GML>#define charMatch {
first = "qwertyuiop";
// Determining if the first string starts with second string
second = "qwerty";
if (string_pos(second, first) > 0) {
show_message("'" + first + "' starts with '" + second + "'");
} else {
show_message("'" + first + "' does not start with '" + second + "'");
}
second = "wert"
// Determining if the first string contains the second string at any location
// Print the location of the match for part 2
if (string_pos(second, first) > 0) {
show_message("'" + first + "' contains '" + second + "' at position " + string(x));
} else {
show_message("'" + first + "' does not contain '" + second + "'");
}
// Handle multiple occurrences of a string for part 2.
x = string_count(second, first);
show_message("'" + first + "' contains " + string(x) + " instances of '" + second + "'");
// Determining if the first string ends with the second string
second = "random garbage"
temp = string_copy(first,
(string_length(first) - string_length(second)) + 1,
string_length(second));
if (temp == second) {
show_message("'" + first + "' ends with '" + second + "'");
} else {
show_message("'" + first + "' does not end with '" + second + "'");
}
}</lang>
- Output:
(in message boxes, 1 per line)
'qwertyuiop' starts with 'qwerty' 'qwertyuiop' contains 'wert' at position 0 'qwertyuiop' contains 1 instances of 'wert' 'qwertyuiop' does not end with 'random garbage'
Go
<lang go>package main
import (
"fmt" "strings"
)
func match(first, second string) {
fmt.Printf("1. %s starts with %s: %t\n",
first, second, strings.HasPrefix(first, second))
i := strings.Index(first, second)
fmt.Printf("2. %s contains %s: %t,\n", first, second, i >= 0)
if i >= 0 {
fmt.Printf("2.1. at location %d,\n", i)
for start := i+1;; {
if i = strings.Index(first[start:], second); i < 0 {
break
}
fmt.Printf("2.2. at location %d,\n", start+i)
start += i+1
}
fmt.Println("2.2. and that's all")
}
fmt.Printf("3. %s ends with %s: %t\n",
first, second, strings.HasSuffix(first, second))
}
func main() {
match("abracadabra", "abr")
}</lang>
- Output:
1. abracadabra starts with abr: true 2. abracadabra contains abr: true, 2.1. at location 0, 2.2. at location 7, 2.2. and that's all 3. abracadabra ends with abr: false
Groovy
Examples: <lang groovy>assert "abcd".startsWith("ab") assert ! "abcd".startsWith("zn") assert "abcd".endsWith("cd") assert ! "abcd".endsWith("zn") assert "abab".contains("ba") assert ! "abab".contains("bb")
assert "abab".indexOf("bb") == -1 // not found flag
assert "abab".indexOf("ab") == 0
def indicesOf = { string, substring ->
if (!string) { return [] }
def indices = [-1]
while (true) {
indices << string.indexOf(substring, indices.last()+1)
if (indices.last() == -1) break
}
indices[1..<(indices.size()-1)]
} assert indicesOf("abab", "ab") == [0, 2] assert indicesOf("abab", "ba") == [1] assert indicesOf("abab", "xy") == []</lang>
All assertions pass, so there is no output.
Haskell
<lang haskell>> import Data.List > "abc" `isPrefixOf` "abcdefg" True > "efg" `isSuffixOf` "abcdefg" True > "bcd" `isInfixOf` "abcdefg" True > "abc" `isInfixOf` "abcdefg" -- Prefixes and suffixes are also infixes True > let infixes a b = findIndices (isPrefixOf a) $ tails b > infixes "ab" "abcdefabqqab" [0,6,10]</lang>
Icon and Unicon
<lang Icon>procedure main()
write("Matching s2 :=",image(s2 := "ab")," within s1:= ",image(s1 := "abcdabab"))
write("Test #1 beginning ",if match(s2,s1) then "matches " else "failed")
writes("Test #2 all matches at positions [")
every writes(" ",find(s2,s1)|"]\n")
write("Test #3 ending ", if s1[0-:*s2] == s2 then "matches" else "fails")
end</lang>
- Output:
Matching s2 :="ab" within s1:= "abcdabab" Test #1 beginning matches Test #2 all matches at positions [ 1 5 7 ] Test #3 ending matches
J
<lang j>startswith=: ] -: ({.~ #) contains=: +./@:E.~ endswith=: ] -: ({.~ -@#)</lang>
Example use:
<lang j> 'abcd' startswith 'ab' 1
'abcd' startswith 'cd'
0
'abcd' endswith 'ab'
0
'abcd' endswith 'cd'
1
'abcd' contains 'bb'
0
'abcd' contains 'ab'
1
'abcd' contains 'bc'
1
'abab' contains 'ab'
1
'abab' I.@E.~ 'ab' NB. find starting indicies
0 2</lang>
Note that these verbs contain no constraints restricting them to sequences of characters and so also apply to arrays of type other than character: <lang j> 0 1 2 3 startswith 0 1 NB. integer 1
4.2 5.1 1.3 9 3 contains 1.3 4.2 NB. floating point
0
4.2 5.1 1.3 4.2 9 3 contains 1.3 4.2
1</lang>
Java
<lang java>"abcd".startsWith("ab") //returns true "abcd".endsWith("zn") //returns false "abab".contains("bb") //returns false "abab".contains("ab") //returns true int loc = "abab".indexOf("bb") //returns -1 loc = "abab".indexOf("ab") //returns 0 loc = "abab".indexOf("ab",loc+1) //returns 2</lang>
// -----------------------------------------------------------// public class JavaApplication6 {
public static void main(String[] args) {
String strOne = "complexity";
String strTwo = "udacity";
//
stringMatch(strOne, strTwo);
}
public static void stringMatch(String one, String two) {
boolean match = false;
if (one.charAt(0) == two.charAt(0)) {
System.out.println(match = true); // returns true
} else {
System.out.println(match); // returns false
}
for (int i = 0; i < two.length(); i++) {
int temp = i;
for (int x = 0; x < one.length(); x++) {
if (two.charAt(temp) == one.charAt(x)) {
System.out.println(match = true); //returns true
i = two.length();
}
}
}
int num1 = one.length() - 1;
int num2 = two.length() - 1;
if (one.charAt(num1) == two.charAt(num2)) {
System.out.println(match = true);
} else {
System.out.println(match = false);
}
}
}
JavaScript
<lang javascript>var stringA = "tacoloco"
, stringB = "co" , q1, q2, q2multi, m , q2matches = []
// stringA starts with stringB q1 = stringA.substring(0, stringB.length) == stringB
// stringA contains stringB q2 = stringA.indexOf(stringB)
// multiple matches q2multi = new RegExp(stringB,'g')
while(m = q2multi.exec(stringA)){ q2matches.push(m.index) }
// stringA ends with stringB q3 = stringA.substr(-stringB.length) == stringB
console.log("1: Does '"+stringA+"' start with '"+stringB+"'? " + ( q1 ? "Yes." : "No.")) console.log("2: Is '"+stringB+"' contained in '"+stringA+"'? " + (~q2 ? "Yes, at index "+q2+"." : "No.")) if (~q2 && q2matches.length > 1){ console.log(" In fact, it happens "+q2matches.length+" times within '"+stringA+"', at index"+(q2matches.length > 1 ? "es" : "")+" "+q2matches.join(', ')+".") } console.log("3: Does '"+stringA+"' end with '"+stringB+"'? " + ( q3 ? "Yes." : "No."))</lang>
- Output:
1: Does 'tacoloco' start with 'co'? No. 2: Is 'co' contained in 'tacoloco'? Yes, at index 2. In fact, it happens 2 times within 'tacoloco', at indexes 2, 6. 3: Does 'tacoloco' end with 'co'? Yes.
jq
Using the builtins of jq 1.4 and later: <lang jq># startswith/1 is boolean: "abc" | startswith("ab")
- => true</lang>
<lang jq># index/1 returns the index or null,
- so the jq test "if index(_) then ...." can be used
- without any type conversion.
"abcd" | index( "bc")
- => 1</lang>
<lang jq># endswith/1 is also boolean: "abc" | endswith("bc")
- => true</lang>
Using the regex functions available in jq 1.5: <lang jq>"abc" | test( "^ab")
"abcd" | test("bc")
"abcd" | test("cd$")</lang>
Multiple Occurrences
To determine all the indices of one string in another: <lang sh># In jq 1.4 or later: jq -n '"abcdabcd" | indices("bc")' [
1, 5
]</lang>
In jq 1.5, the regex function match/1 can also be used: <lang sh>$ jq -n '"abcdabcd" | match("bc"; "g") | .offset' 1 5</lang>
Julia
<lang julia> startswith("abcd","ab") #returns true findfirst("ab", "abcd") #returns 1:2, indices range where string was found endswith("abcd","zn") #returns false match(r"ab","abcd") != Nothing #returns true where 1st arg is regex string for r in eachmatch(r"ab","abab") println(r.offset) end #returns 1, then 3 matching the two starting indices where the substring was found </lang>
K
<lang k>startswith: {:[0<#p:_ss[x;y];~*p;0]} endswith: {0=(-#y)+(#x)-*_ss[x;y]} contains: {0<#_ss[x;y]}</lang>
Example:
<lang k> startswith["abcd";"ab"] 1
startswith["abcd";"bc"]
0
endswith["abcd";"cd"]
1
endswith["abcd";"bc"]
0
contains["abcdef";"cde"]
1
contains["abcdef";"bdef"]
0
_ss["abcdabceabc";"abc"] / location of matches
0 4 8</lang>
Kotlin
<lang scala>// version 1.0.6
fun main(args: Array<String>) {
val s1 = "abracadabra"
val s2 = "abra"
println("$s1 begins with $s2 : ${s1.startsWith(s2)}")
println("$s1 ends with $s2 : ${s1.endsWith(s2)}")
val b = s2 in s1
print("$s1 contains $s2 : $b")
if (b) println(" at locations ${s1.indexOf(s2) + 1} and ${s1.lastIndexOf(s2) + 1}")
else println()
}</lang>
- Output:
abracadabra begins with abra : true abracadabra ends with abra : true abracadabra contains abra : true at locations 1 and 8
Ksh
<lang ksh>
- !/bin/ksh
exec 2> /tmp/String_matching.err
- String matching
- # 1. Determine if the first string starts with second string.
- # 2. Determine if the first string contains the second string at any location
- # 3. Determine if the first string ends with the second string
- # 4. Print the location of the match for part 2
- # 5. Handle multiple occurrences of a string for part 2
- # Variables:
typeset -a bounds=( [0]="no Match" [1]="Starts with" [255]="Ends with" )
typeset -a string=( "Hello" "hello world" "William Williams" "Yabba dabba do" ) typeset -a substr=( "Hell" "Do" "abba" "Will" "orld" )
- # Functions:
- # Function _bounds(str, substr) - return 1 for starts with 255 for endswith
function _bounds { typeset _str ; _str="$1" typeset _sub ; _sub="$2"
typeset _FALSE _STARTS _ENDS ; integer _FALSE=0 _STARTS=1 _ENDS=255
[[ "${_str}" == "${_sub}"* ]] && return ${_STARTS} [[ "${_str}" == *"${_sub}" ]] && return ${_ENDS} return ${_FALSE} }
- # Function _contains(str, substr) - return 0 no match arr[pos1 ... posn]
function _contains { typeset _str ; _str="$1" typeset _sub ; _sub="$2" typeset _arr ; nameref _arr="$3"
typeset _FALSE _TRUE _i _match _buff ; integer _FALSE=0 _TRUE=1 _i _match
[[ "${_str}" != *"${_sub}"* ]] && return ${_FALSE}
for ((_i=0; _i<=${#_str}-${#_sub}; _i++)); do _buff=${_str:${_i}:$((${#_str}-_i))} [[ ${_buff} != ${_buff#${_sub}} ]] && _arr+=( $(( _i+1 )) ) done return ${_TRUE} }
######
- main #
######
integer i j rc typeset -a posarr
for ((i=0; i<${#string[*]}; i++)); do for ((j=0; j<${#substr[*]}; j++)); do _bounds "${string[i]}" "${substr[j]}" ; rc=$? print "${string[i]} ${bounds[rc]} ${substr[j]}"
_contains "${string[i]}" "${substr[j]}" posarr ; rc=$? ((! rc)) && print "${string[i]} ${substr[j]} ${bounds[rc]}es" && continue
print "${string[i]} + ${substr[j]} ${#posarr[*]} matches at ${posarr[*]}" unset posarr ; typeset -a posarr done done</lang>
- Output:
Hello Starts with Hell Hello + Hell 1 matches at 1 Hello no Match Do Hello Do no Matches Hello no Match abba Hello abba no Matches Hello no Match Will Hello Will no Matches Hello no Match orld Hello orld no Matches hello world no Match Hell hello world Hell no Matches hello world no Match Do hello world Do no Matches hello world no Match abba hello world abba no Matches hello world no Match Will hello world Will no Matches hello world Ends with orld hello world + orld 1 matches at 8 William Williams no Match Hell William Williams Hell no Matches William Williams no Match Do William Williams Do no Matches William Williams no Match abba William Williams abba no Matches William Williams Starts with Will William Williams + Will 2 matches at 1 9 William Williams no Match orld William Williams orld no Matches Yabba dabba do no Match Hell Yabba dabba do Hell no Matches Yabba dabba do no Match Do Yabba dabba do Do no Matches Yabba dabba do no Match abba Yabba dabba do + abba 2 matches at 2 8 Yabba dabba do no Match Will Yabba dabba do Will no Matches Yabba dabba do no Match orld
Yabba dabba do orld no Matches
LabVIEW
These images solve the task's requirements in order.
This image is a VI Snippet, an executable image of LabVIEW code. The LabVIEW version is shown on the top-right hand corner. You can download it, then drag-and-drop it onto the LabVIEW block diagram from a file browser, and it will appear as runnable, editable code.
Lang5
<lang lang5>: 2array 2 compress ; : bi* '_ set dip _ execute ; : bi@ dup bi* ;
- comb "" split ; : concat "" join ; : dip swap '_ set execute _ ;
- first 0 extract swap drop ; : flip comb reverse concat ;
- contains
swap 'comb bi@ length do # create a matrix.
1 - "dup 1 1 compress rotate" dip dup 0 == if break then
loop drop length compress swap drop
"length 1 -" bi@ rot 0 0 "'2array dip" '2array bi* swap 2array slice reverse
: concat.(*) concat ;
'concat "'concat. apply" bi* eq 1 1 compress index collapse
length if expand drop else drop 0 then ; # r: position.
- end-with 'flip bi@ start-with ;
- start-with 'comb bi@ length rot swap iota subscript 'concat bi@ eq ;
"rosettacode" "rosetta" start-with . # 1 "rosettacode" "taco" contains . # 5 "rosettacode" "ocat" contains . # 0 "rosettacode" "edoc" end-with . # 0 "rosettacode" "code" contains . # 7</lang>
Lasso
<lang Lasso>local(
a = 'a quick brown peanut jumped over a quick brown fox', b = 'a quick brown'
)
//Determining if the first string starts with second string
- a->beginswith(#b) // true
//Determining if the first string contains the second string at any location
- a >> #b // true
- a->contains(#b) // true
//Determining if the first string ends with the second string
- a->endswith(#b) // false</lang>
Liberty BASIC
<lang lb>'1---Determining if the first string starts with second string st1$="first string" st2$="first" if left$(st1$,len(st2$))=st2$ then
print "First string starts with second string."
end if
'2---Determining if the first string contains the second string at any location '2.1---Print the location of the match for part 2 st1$="Mississippi" st2$="i" if instr(st1$,st2$) then
print "First string contains second string." print "Second string is at location ";instr(st1$,st2$)
end if
'2.2---Handle multiple occurrences of a string for part 2. pos=instr(st1$,st2$) while pos
count=count+1 pos=instr(st1$,st2$,pos+len(st2$))
wend print "Number of times second string appears in first string is ";count
'3---Determining if the first string ends with the second string st1$="first string" st2$="string" if right$(st1$,len(st2$))=st2$ then
print "First string ends with second string."
end if </lang>
Lingo
<lang lingo>a = "Hello world!" b = "Hello"
-- Determining if the first string starts with second string put a starts b -- 1
-- Determining if the first string contains the second string at any location put a contains b -- 1
-- Determining if the first string ends with the second string put a.char[a.length-b.length+1..a.length] = b -- 0
b = "world!" put a.char[a.length-b.length+1..a.length] = b -- 1
-- Print the location of the match for part 2 put offset(b, a) -- 7</lang>
Logo
<lang logo>to starts.with? :sub :thing
if empty? :sub [output "true] if empty? :thing [output "false] if not equal? first :sub first :thing [output "false] output starts.with? butfirst :sub butfirst :thing
end
to ends.with? :sub :thing
if empty? :sub [output "true] if empty? :thing [output "false] if not equal? last :sub last :thing [output "false] output ends.with? butlast :sub butlast :thing
end
show starts.with? "dog "doghouse ; true show ends.with? "house "doghouse ; true show substring? "gho "doghouse ; true (built-in)</lang>
Lua
<lang lua>s1 = "string" s2 = "str" s3 = "ing" s4 = "xyz"
print( "s1 starts with s2: ", string.find( s1, s2 ) == 1 ) print( "s1 starts with s3: ", string.find( s1, s3 ) == 1, "\n" )
print( "s1 contains s3: ", string.find( s1, s3 ) ~= nil ) print( "s1 contains s3: ", string.find( s1, s4 ) ~= nil, "\n" )
print( "s1 ends with s2: ", select( 2, string.find( s1, s2 ) ) == string.len( s1 ) ) print( "s1 ends with s3: ", select( 2, string.find( s1, s3 ) ) == string.len( s1 ) )</lang>
M2000 Interpreter
<lang M2000 Interpreter> Module StringMatch {
A$="Hello World"
Print A$ ~ "Hello*"
Print A$ ~ "*llo*"
p=Instr(A$, "llo")
Print p=3
\\ Handle multiple occurance for "o"
p=Instr(A$, "o")
While p > 0 {
Print "position:";p;{ for "o"}
p=Instr(A$, "o", p+1)
}
Print A$ ~ "*orld"
} StringMatch </lang>
- Output:
True
True
True
position:5 for "o"
position:8 for "o"
True
Maple
These facilities are all to be found in the StringTools package in Maple. <lang Maple> > with( StringTools ): # bind package exports at the top-level > s := "dzrIemaWWIMidXYZwGiqkOOn": > s[1..4]; # pick a prefix
"dzrI"
> IsPrefix( s[ 1 .. 4 ], s ); # check it
true
> s[ -4 .. -1 ]; # pick a suffix
"kOOn"
> IsSuffix( s[ -4 .. -1 ], s ); # check it
true
> p := Search( "XYZ", s ); # find a substring
p := 14
> s[ p .. p + 2 ]; # check
"XYZ"
> SearchAll( [ "WWI", "XYZ" ], s ); # search for multiple patterns
[8, 1], [14, 2]
> to 3 do s := cat( s, s ) end: length( s ); # build a longer string by repeated doubling
192
> p := SearchAll( "XYZ", s ); # find all occurrences
p := 14, 38, 62, 86, 110, 134, 158, 182
> {seq}( s[ i .. i + 2 ], i = p ); # check them
{"XYZ"}
</lang> The StringTools package also contains facilities for regular expression matching, but for fixed string patterns, the Search and SearchAll tools are much faster.
Mathematica /Wolfram Language
<lang Mathematica>StartWith[x_, y_] := MemberQ[Flatten[StringPosition[x, y]], 1] EndWith[x_, y_] := MemberQ[Flatten[StringPosition[x, y]], StringLength[x]] StartWith["XYZaaabXYZaaaaXYZXYZ", "XYZ"] EndWith["XYZaaabXYZaaaaXYZXYZ", "XYZ"] StringPosition["XYZaaabXYZaaaaXYZXYZ", "XYZ"]</lang>
- Output:
True
True
{{1,3},{8,10},{15,17},{18,20}}
MATLAB / Octave
<lang Matlab>
% 1. Determining if the first string starts with second string
strcmp(str1,str2,length(str2))
% 2. Determining if the first string contains the second string at any location
~isempty(strfind(s1,s2))
% 3. Determining if the first string ends with the second string
( (length(str1)>=length(str2)) && strcmp(str1(end+[1-length(str2):0]),str2) )
% 1. Print the location of the match for part 2
disp(strfind(s1,s2))
% 2. Handle multiple occurrences of a string for part 2.
ix = strfind(s1,s2); % ix is a vector containing the starting positions of s2 within s1 </lang>
min
One way might be:
<lang min>(indexof 0 ==) :starts-with? (indexof -1 !=) :contains? ((/ $/) swap 1 insert "" join regex ("") !=) :ends-with?
"minimalistic" "min" starts-with? puts! "minimalistic" "list" contains? puts! "minimalistic" "list" ends-with? puts!</lang>
- Output:
true true false
MiniScript
We first extend the built-in string class with three new methods, and then demonstrate their use on some sample strings.
<lang MiniScript>string.startsWith = function(s)
return self.len >= s.len and s[:s.len] == s
end function
string.endsWith = function(s)
return self.len >= s.len and s[-s.len:] == s
end function
string.findAll = function(s)
result = []
after = null
while true
foundPos = self.indexOf(s, after)
if foundPos == null then return result
result.push foundPos
after = foundPos + s.len - 1
end while
end function
first = "The brown dog jumped jumped and jumped" second = "jumped"
firstQ = """" + first + """" // (first string, in quotes) secondQ = """" + second + """" doesOrNot = [" does not ", " does "]
print firstQ + doesOrNot[first.startsWith(second)] + "start with " + secondQ print
found = first.findAll(second) if not found then
print firstQ + " does not contain " + secondQ + " anywhere"
else
for pos in found
print firstQ + " is found at position " + pos + " in " + secondQ
end for
end if print
print firstQ + doesOrNot[first.endsWith(second)] + "end with " + secondQ</lang>
- Output:
"The brown dog jumped jumped and jumped" does start with "jumped" "The brown dog jumped jumped and jumped" is found at position 14 in "jumped" "The brown dog jumped jumped and jumped" is found at position 21 in "jumped" "The brown dog jumped jumped and jumped" is found at position 32 in "jumped" "The brown dog jumped jumped and jumped" does end with "jumped"
NetRexx
<lang NetRexx>/* NetRexx */ options replace format comments java crossref savelog symbols
lipsum = x_ = 0 x_ = x_ + 1; lipsum[0] = x_; lipsum[x_] = 'Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.' x_ = x_ + 1; lipsum[0] = x_; lipsum[x_] = lipsum[1].reverse
srch = srch[1] = 'Lorem ipsum dolor sit amet' srch[2] = 'consectetur adipisicing elit' srch[3] = 'dolore magna aliqua.'
loop j_ = 1 to lipsum[0]
x1 = lipsum[j_].pos(srch[1]) x2 = lipsum[j_].pos(srch[2]) x3 = lipsum[j_].lastpos(srch[3])
report(x1 = 1, lipsum[j_], srch[1], 'Test string starts with search string:', 'Test string does not start with search string:') report(x2 > 0, lipsum[j_], srch[2], 'Search string located in test string at position:' x2, 'Search string not found within test string:') report(x3 \= srch[3].length, lipsum[j_], srch[3], 'Test string ends with search string:', 'Test string does not start with search string:') end j_
many = x_ = 0 x_ = x_ + 1; many[0] = x_; many[x_] = 'How many times does "many times" occur in this string?' x_ = x_ + 1; many[0] = x_; many[x_] = 'How often does "many times" occur in this string?' x_ = x_ + 1; many[0] = x_; many[x_] = 'How often does it occur in this string?' srch[4] = 'many times'
loop j_ = 1 to many[0]
o_ = 0 k_ = 0 loop label dups until o_ = 0 o_ = many[j_].pos(srch[4], o_ + 1) if o_ \= 0 then k_ = k_ + 1 end dups report(k_ > 0, many[j_], srch[4], 'Number of times search string occurs:' k_, 'Search string not found') end j_
method report(state = boolean, ts, ss, testSuccess, testFailure) public static
if state then say testSuccess else say testFailure say ' Test string:' ts say ' Search string:' ss say
return
</lang>
NewLISP
<lang NewLISP>(setq str "abcdefbcghi")
- test if str starts with "ab"
(starts-with str "ab")
- find "bc" inside str
(find "bc" str)
- test if str ends with "ghi"
(ends-with str "ghi")
- find all positions of pattern inside str
(define (find-all-pos pattern str)
(let ((idx -1) (pos '()))
(while (setq idx (find pattern str 0 (+ idx 1)))
(push idx pos -1))))
(find-all-pos "bc" str)</lang>
Nim
<lang nim>import strutils
let s = "The quick brown fox" if s.startsWith("The quick"):
echo "Starts with “The quick”."
if s.endsWith("brown Fox"):
echo "Ends with “brown fox”."
if s.contains(" brown "):
echo "Contains “ brown ”."
if "quick" in s:
echo "Contains “quick”." # Alternate form for "contains".
let pos = find(s, " brown ") # -1 if not found. if pos >= 0:
echo "“ brown ” is located at position: " & $pos</lang>
- Output:
Starts with “The quick”. Contains “ brown ”. Contains “quick”. “ brown ” is located at position: 9
Objeck
<lang objeck> bundle Default {
class Matching {
function : Main(args : System.String[]) ~ Nil {
"abcd"->StartsWith("ab")->PrintLine(); # returns true
"abcd"->EndsWith("zn")->PrintLine(); # returns false
("abab"->Find("bb") <> -1)->PrintLine(); # returns false
("abab"->Find("ab") <> -1)->PrintLine(); # returns true
loc := "abab"->Find("bb"); # returns -1
loc := "abab"->Find("ab"); # returns 0
loc := "abab"->Find("ab", loc + 1); # returns 2
}
}
} </lang>
Objective-C
<lang objc>[@"abcd" hasPrefix:@"ab"] //returns true [@"abcd" hasSuffix:@"zn"] //returns false int loc = [@"abab" rangeOfString:@"bb"].location //returns -1 loc = [@"abab" rangeOfString:@"ab"].location //returns 0 loc = [@"abab" rangeOfString:@"ab" options:0 range:NSMakeRange(loc+1, [@"abab" length]-(loc+1))].location //returns 2</lang>
OCaml
<lang ocaml>let match1 s1 s2 =
let len1 = String.length s1 and len2 = String.length s2 in if len1 < len2 then false else let sub = String.sub s1 0 len2 in (sub = s2)</lang>
testing in the top-level:
# match1 "Hello" "Hello World!" ;; - : bool = false # match1 "Hello World!" "Hello" ;; - : bool = true
<lang ocaml>let match2 s1 s2 =
let len1 = String.length s1
and len2 = String.length s2 in
if len1 < len2 then false else
let rec aux i =
if i < 0 then false else
let sub = String.sub s1 i len2 in
if (sub = s2) then true else aux (pred i)
in
aux (len1 - len2)</lang>
# match2 "It's raining, Hello World!" "umbrella" ;; - : bool = false # match2 "It's raining, Hello World!" "Hello" ;; - : bool = true
<lang ocaml>let match3 s1 s2 =
let len1 = String.length s1 and len2 = String.length s2 in if len1 < len2 then false else let sub = String.sub s1 (len1 - len2) len2 in (sub = s2)</lang>
# match3 "Hello World" "Hello" ;; - : bool = false # match3 "Hello World" "World" ;; - : bool = true
<lang ocaml>let match2_loc s1 s2 =
let len1 = String.length s1
and len2 = String.length s2 in
if len1 < len2 then (false, -1) else
let rec aux i =
if i < 0 then (false, -1) else
let sub = String.sub s1 i len2 in
if (sub = s2) then (true, i) else aux (pred i)
in
aux (len1 - len2)</lang>
# match2_loc "The sun's shining, Hello World!" "raining" ;; - : bool * int = (false, -1) # match2_loc "The sun's shining, Hello World!" "shining" ;; - : bool * int = (true, 10)
<lang ocaml>let match2_num s1 s2 =
let len1 = String.length s1
and len2 = String.length s2 in
if len1 < len2 then (false, 0) else
let rec aux i n =
if i < 0 then (n <> 0, n) else
let sub = String.sub s1 i len2 in
if (sub = s2)
then aux (pred i) (succ n)
else aux (pred i) (n)
in
aux (len1 - len2) 0</lang>
# match2_num "This cloud looks like a camel, \
that other cloud looks like a llama" "stone" ;;
- : bool * int = (false, 0)
# match2_num "This cloud looks like a camel, \
that other cloud looks like a llama" "cloud" ;;
- : bool * int = (true, 2)
Oforth
<lang Oforth>: stringMatching(s1, s2) | i |
s2 isAllAt(s1, 1) ifTrue: [ System.Out s1 << " begins with " << s2 << cr ] s2 isAllAt(s1, s1 size s2 size - 1 + ) ifTrue: [ System.Out s1 << " ends with " << s2 << cr ]
s1 indexOfAll(s2) ->i i ifNotNull: [ System.Out s1 << " includes " << s2 << " at position : " << i << cr ]
"\nAll positions : " println
1 ->i
while (s1 indexOfAllFrom(s2, i) dup ->i notNull) [
System.Out s1 << " includes " << s2 << " at position : " << i << cr
i s2 size + ->i
] ;</lang>
- Output:
> "arduinoardblobard", "ard" stringMatching arduinoardblobard begins with ard arduinoardblobard ends with ard arduinoardblobard includes ard at position : 1 All positions : arduinoardblobard includes ard at position : 1 arduinoardblobard includes ard at position : 8 arduinoardblobard includes ard at position : 15
OxygenBasic
<lang oxygenbasic> string s="sdfkjhgsdfkdfgkbopefioqwurti487sdfkrglkjfs9wrtgjglsdfkdkjcnmmb.,msfjflkjsdfk"
string f="sdfk"
string cr=chr(13)+chr(10),tab=chr(9)
string pr="FIND STRING LOCATIONS" cr cr
sys a=0, b=1, count=0, ls=len(s), lf=len(f)
do
a=instr b,s,f if a=0 then exit do count++ if a=1 then pr+="Begins with keyword" cr pr+=count tab a cr if a=ls-lf+1 then pr+="Ends with keyword at " a cr b=a+1
end do
pr+=cr "Total matches: " count cr
print pr
'FIND STRING LOCATIONS ' 'Begins with keyword '1 1 '2 8 '3 32 '4 51 '5 73 'Ends with keyword at 73 ' 'Total matches: 5 </lang>
PARI/GP
This meets the first but not the second of the optional requirements. Note that GP treats any nonzero value as true so the location found by contains() can be ignore if not needed. <lang parigp>startsWith(string, prefix)={
string=Vec(string); prefix=Vec(prefix); if(#prefix > #string, return(0)); for(i=1,#prefix,if(prefix[i]!=string[i], return(0))); 1
}; contains(string, inner)={
my(good);
string=Vec(string);
inner=Vec(inner);
for(i=0,#string-#inner,
good=1;
for(j=1,#inner,
if(inner[j]!=string[i+j], good=0; break)
);
if(good, return(i+1))
);
0
}; endsWith(string, suffix)={
string=Vec(string); suffix=Vec(suffix); if(#suffix > #string, return(0)); for(i=1,#suffix,if(prefix[i]!=string[i+#string-#suffix], return(0))); 1
};</lang>
Perl
Using regexes:
<lang perl>$str1 =~ /^\Q$str2\E/ # true if $str1 starts with $str2 $str1 =~ /\Q$str2\E/ # true if $str1 contains $str2 $str1 =~ /\Q$str2\E$/ # true if $str1 ends with $str2</lang>
Using index:
<lang perl>index($str1, $str2) == 0 # true if $str1 starts with $str2 index($str1, $str2) != -1 # true if $str1 contains $str2 rindex($str1, $str2) == length($str1) - length($str2) # true if $str1 ends with $str2</lang>
Using substr:
<lang perl>substr($str1, 0, length($str2)) eq $str2 # true if $str1 starts with $str2 substr($str1, - length($str2)) eq $str2 # true if $str1 ends with $str2</lang>
Bonus task (printing all positions where $str2 appears in $str1):
<lang perl>print $-[0], "\n" while $str1 =~ /\Q$str2\E/g; # using a regex</lang> <lang perl>my $i = -1; print $i, "\n" while ($i = index $str1, $str2, $i + 1) != -1; # using index</lang>
Phix
constant word = "the", -- (also try this with "th"/"he") sentence = "the last thing the man said was the" -- sentence = "thelastthingthemansaidwasthe" -- (practically the same results) -- A common, but potentially inefficient idiom for checking for a substring at the start is: if match(word,sentence)=1 then ?"yes(1)" end if -- A more efficient method is to test the appropriate slice if length(sentence)>=length(word) and sentence[1..length(word)]=word then ?"yes(2)" end if -- Which is almost identical to checking for a word at the end if length(sentence)>=length(word) and sentence[-length(word)..-1]=word then ?"yes(3)" end if -- Or sometimes you will see this, a tiny bit more efficient: if length(sentence)>=length(word) and match(word,sentence,length(sentence)-length(word)+1) then ?"yes(4)" end if -- Finding all occurences is a snap: integer r = match(word,sentence) while r!=0 do ?r r = match(word,sentence,r+1) end while -- or equivalently: ?match_all(word,sentence)
- Output:
"yes(1)"
"yes(2)"
"yes(3)"
"yes(4)"
1
16
33
{1,16,33}
PHP
<lang php><?php /**********************************************************************************
- This program gets needle and haystack from the caller (chm.html) (see below)
- and checks for occurrences of the needle in the haystack
- 02.05.2013 Walter Pachl
- Comments or Suggestions welcome
- /
$haystack = $_POST['haystack']; if ($haystack==) {$haystack='no haystack given';} $needle = $_POST['needle']; if ($needle==) {$needle='no needle given';}
function rexxpos($h,$n) {
$pos = strpos($h,$n);
if ($pos === false) { $pos=-1; }
else { $pos=$pos+1; }
return ($pos);
}
$pos=rexxpos($haystack,$needle); $tx1 = ""; if ($pos==-1){ $n=0; } // not found else { $n=1; } // found once (so far) // Special cases if ($pos==1){ $tx1="needle found to be the start of the haystack"; } if ($pos==strlen($haystack)-strlen($needle)+1)
{ $tx1="needle found at end of haystack"; }
if ($n>0) { // look for other occurrences
$pl=$pos; // list of positions
$p=$pos; //
$x="*************************************";
$h=$haystack;
while ($p>0) {
$h=substr($x,0,$p).substr($h,$p);
$p=rexxpos($h,$needle);
if ( $p>0 ) { $n=$n+1; $pl=$pl.", ".$p; }
}
if ($n==1) { $txt="needle found once in haystack, position: $pl."; }
else if ($n==2) { $txt="needle found twice in haystack, position(s): $pl."; }
else { $txt="needle found $n times in haystack, position(s): $pl."; }
} else { $txt="needle not found in haystack."; } ?> <html>
<head>
<title>Character Matching</title>
<meta name="author" content="Walter Pachl">
<meta name="date" content="02.05.2013">
<style>
p { font: 120% courier; }
</style>
</head>
<body>
Haystack: '<?php echo "$haystack" ?>'
Needle: '<?php echo "$needle" ?>'
<?php echo "$txt" ?>
<?php echo "$tx1" ?>
</body>
</html></lang> <lang php><?php <!DOCTYPE html> <html>
<head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <title>Character matching</title> </head> <body> <form id="test" name="test" method="post" action="chmx.php">
Character matching
Given two strings, demonstrate the following 3 types of matchings:
- Determining if the first string starts with second string
- Determining if the first string contains the second string at any location
- Determining if the first string ends with the second string
Optional requirements:
- Print the location of the match(es) for part 2
- Handle multiple occurrences of a string for part 2.
Haystack: <input type="text" name="haystack" size="80">
Needle: <input type="text" name="needle" size="80">
Press <input name="Submit" type="submit" class="erfolg" value="CHECK"/> to invoke chmx.php.
</form> </body>
</html></lang>
PicoLisp
<lang PicoLisp>: (pre? "ab" "abcd") -> "abcd"
- (pre? "xy" "abcd")
-> NIL
- (sub? "bc" "abcd")
-> "abcd"
- (sub? "xy" "abcd")
-> NIL
- (tail (chop "cd") (chop "abcd"))
-> ("c" "d")
- (tail (chop "xy") (chop "abcd"))
-> NIL
(de positions (Pat Str)
(setq Pat (chop Pat))
(make
(for ((I . L) (chop Str) L (cdr L))
(and (head Pat L) (link I)) ) ) )
- (positions "bc" "abcdabcd")
-> (2 6)</lang>
PL/I
<lang PL/I> /* Let s be one string, t be the other that might exist within s. */
/* 8-1-2011 */
k = index(s, t); if k = 0 then put skip edit (t, ' is nowhere in sight') (a); else if k = 1 then
put skip edit (t, ' starts at the beginning of ', s) (a);
else if k+length(t)-1 = length(s) then
put skip edit (t, ' is at the end of ', s) (a);
else put skip edit (t, ' is within ', s) (a);
if k > 0 then put skip edit (t, ' starts at position ', k) (a); </lang>
Optional extra:
<lang PL/I> /* Handle multiple occurrences. */
n = 1;
do forever;
k = index(s, t, n);
if k = 0 then
do;
if n = 1 then put skip list (t, ' is nowhere in sight');
stop;
end;
else if k = 1 then
put skip edit ('<', t, '> starts at the beginning of ', s) (a);
else if k+length(t)-1 = length(s) then
put skip edit ('<', t, '> is at the end of ', s) (a);
else put skip edit ('<', t, '> is within ', s) (a);
n = k + length(t);
if k > 0 then
put skip edit ('<', t, '> starts at position ', trim(k)) (a);
else stop;
end;
</lang>
PowerShell
<lang Powershell> "spicywiener".StartsWith("spicy") "spicywiener".Contains("icy") "spicywiener".EndsWith("wiener") "spicywiener".IndexOf("icy") [regex]::Matches("spicywiener", "i").count </lang>
- Output:
True True True 2 2
Prolog
<lang prolog>
- - system:set_prolog_flag(double_quotes,codes) .
- - [library(lists)] .
%! starts_with(FIRSTz,SECONDz) % % True if `SECONDz` is the beginning of `FIRSTz` .
starts_with(FIRSTz,SECONDz)
- -
lists:append(SECONDz,_,FIRSTz) .
%! contains(FIRSTz,SECONDz) % % True once if `SECONDz` is contained within `FIRSTz` at one or more positions .
contains(FIRSTz,SECONDz)
- -
contains(FIRSTz,SECONDz,_) , ! .
%! contains(FIRSTz,SECONDz,NTH1) % % True if `SECONDz` is contained within `FIRSTz` at position `NTH1` .
contains(FIRSTz,SECONDz,NTH1)
- -
lists:append([PREFIXz,SECONDz,_SUFFIXz_],FIRSTz) , prolog:length(PREFIXz,NTH0) , NTH1 is NTH0 + 1 .
%! ends_with(FIRSTz,SECONDz) % % True if `SECONDz` is the ending of `FIRSTz` .
ends_with(FIRSTz,SECONDz)
- -
lists:append(_,SECONDz,FIRSTz) .
</lang>
- Output:
?- starts_with("abcdef","abc") .
true .
?- starts_with("abc","abc") .
true .
?- starts_with("abc","abcd") .
false .
?- starts_with("dabc","abc") .
false .
?- starts_with("","") .
true .
?-
?- contains("abcdef","abc") .
true.
?- contains("abcdef","abc",NTH).
NTH = 1 ;
false.
?- contains("abcdef","de",NTH).
NTH = 4 ;
false.
?- contains("abcdef","f",NTH).
NTH = 6 ;
false.
?- contains("abcde","f",NTH).
false.
?- contains("","",NTH).
NTH = 1 ; % wtf ?
false.
?- contains("a","a",NTH).
NTH = 1 ; % wtf ?
false.
?-
?- ends_with("abc","abc") .
true ;
false .
?- ends_with("abc","bc") .
true ;
false .
?- ends_with("abcd","bc") .
false .
?- ends_with("","") .
true ;
false .
?-
PureBasic
<lang PureBasic>Procedure StartsWith(String1$, String2$)
Protected Result If FindString(String1$, String2$, 1) =1 ; E.g Found in possition 1 Result =CountString(String1$, String2$) EndIf ProcedureReturn Result
EndProcedure
Procedure EndsWith(String1$, String2$)
Protected Result, dl=Len(String1$)-Len(String2$) If dl>=0 And Right(String1$, Len(String2$))=String2$ Result =CountString(String1$, String2$) EndIf ProcedureReturn Result
EndProcedure</lang> And a verification <lang PureBasic>If OpenConsole()
PrintN(Str(StartsWith("Rosettacode", "Rosetta"))) ; = 1
PrintN(Str(StartsWith("Rosettacode", "code"))) ; = 0
PrintN(Str(StartsWith("eleutherodactylus cruralis", "e"))) ; = 3
PrintN(Str(EndsWith ("Rosettacode", "Rosetta"))) ; = 0
PrintN(Str(EndsWith ("Rosettacode", "code"))) ; = 1
PrintN(Str(EndsWith ("Rosettacode", "e"))) ; = 2
Print(#CRLF$ + #CRLF$ + "Press ENTER to exit"): Input()
CloseConsole()
EndIf</lang>
An alternate and more complete solution: <lang PureBasic>Procedure startsWith(string1$, string2$)
;returns one if string1$ starts with string2$, otherwise returns zero If FindString(string1$, string2$, 1) = 1 ProcedureReturn 1 EndIf ProcedureReturn 0
EndProcedure
Procedure contains(string1$, string2$, location = 0)
;returns the location of the next occurrence of string2$ in string1$ starting from location, ;or zero if no remaining occurrences of string2$ are found in string1$ ProcedureReturn FindString(string1$, string2$, location + 1)
EndProcedure
Procedure endsWith(string1$, string2$)
;returns one if string1$ ends with string2$, otherwise returns zero Protected ls = Len(string2$) If Len(string1$) - ls >= 0 And Right(string1$, ls) = string2$ ProcedureReturn 1 EndIf ProcedureReturn 0
EndProcedure
If OpenConsole()
PrintN(Str(startsWith("RosettaCode", "Rosetta"))) ; = 1, true
PrintN(Str(startsWith("RosettaCode", "Code"))) ; = 0, false
PrintN("")
PrintN(Str(contains("RosettaCode", "luck"))) ; = 0, no occurrences
Define location
Repeat
location = contains("eleutherodactylus cruralis", "e", location)
PrintN(Str(location)) ;display each occurrence: 1, 3, 7, & 0 (no more occurrences)
Until location = 0
PrintN("")
PrintN(Str(endsWith ("RosettaCode", "Rosetta"))) ; = 0, false
PrintN(Str(endsWith ("RosettaCode", "Code"))) ; = 1, true
Print(#CRLF$ + #CRLF$ + "Press ENTER to exit"): Input()
CloseConsole()
EndIf</lang>
- Output:
1 0 0 1 3 7 0 0 1
Python
<lang python>"abcd".startswith("ab") #returns True "abcd".endswith("zn") #returns False "bb" in "abab" #returns False "ab" in "abab" #returns True loc = "abab".find("bb") #returns -1 loc = "abab".find("ab") #returns 0 loc = "abab".find("ab",loc+1) #returns 2</lang>
Quackery
These work for any nests (i.e. dynamic arrays), not just strings (i.e. nests of chars).
<lang Quackery> [ tuck size split drop = ] is starts ( [ [ --> b )
[ tuck size negate split nip = ] is ends ( [ [ --> b )
[ 2dup = iff true
else
[ over [] = iff false done
2dup starts iff true done
dip behead nip again ]
dip 2drop ] is contains ( [ [ --> b )
[ iff
[ say "true" ]
else
[ say "false" ] ] is echobool ( b --> )
$ "abcdefgh" $ "abc" starts echobool cr
$ "abcdefgh" $ "xyz" starts echobool cr
$ "abcdefgh" $ "fgh" ends echobool cr
$ "abcdefgh" $ "xyz" ends echobool cr
$ "abcdefgh" $ "cde" contains echobool cr
$ "abcdefgh" $ "xyz" contains echobool cr</lang>
- Output:
true false true false true false
Racket
<lang racket>
- lang racket
(require srfi/13) (string-prefix? "ab" "abcd") (string-suffix? "cd" "abcd") (string-contains "abab" "bb") (string-contains "abab" "ba") </lang>
- Output:
#t #t #f 1
Raku
(formerly Perl 6)
Using string methods:
<lang perl6>$haystack.starts-with($needle) # True if $haystack starts with $needle $haystack.contains($needle) # True if $haystack contains $needle $haystack.ends-with($needle) # True if $haystack ends with $needle</lang>
Using regexes:
<lang perl6>so $haystack ~~ /^ $needle / # True if $haystack starts with $needle so $haystack ~~ / $needle / # True if $haystack contains $needle so $haystack ~~ / $needle $/ # True if $haystack ends with $needle</lang>
Using substr:
<lang perl6>substr($haystack, 0, $needle.chars) eq $needle # True if $haystack starts with $needle substr($haystack, *-$needle.chars) eq $needle # True if $haystack ends with $needle</lang>
Bonus task:
<lang perl6>$haystack.match($needle, :g)».from; # List of all positions where $needle appears in $haystack $haystack.indices($needle :overlap); # Also find any overlapping instances of $needle in $haystack</lang>
Retro
<lang Retro>: startsWith? ( $1 $2 - f )
withLength &swap dip 0 swap ^strings'getSubset compare ;
"abcdefghijkl" "abcde" startsWith? "abcdefghijkl" "bcd" startsWith?
"abcdefghijkl" "bcd" ^strings'search "abcdefghijkl" "zmq" ^strings'search
- endsWith? ( $1 $2 - f )
swap withLength + over getLength - compare ;
"abcdefghijkl" "ijkl" endsWith? "abcdefghijkl" "abc" endsWith?</lang>
REXX
Extra coding was added to take care of using plurals in the last output message. <lang rexx>/*REXX program demonstrates some basic character string testing (for matching). */ parse arg A B /*obtain A and B from the command line.*/ say 'string A = ' A /*display string A to the terminal.*/ say 'string B = ' B /* " " B " " " */ say copies('░', 70) /*display a line separator (fence). */ LB= length(B) /*get the length of string B in bytes*/ if left(A, LB)==B then say 'string A starts with string B'
else say "string A doesn't start with string B"
say /* [↓] another method using COMPARE BIF*/ p= pos(B, A) if p==0 then say "string A doesn't contain string B"
else say 'string A contains string B (starting in position' p")"
say if right(A, LB)==B then say 'string A ends with string B'
else say "string A doesn't end with string B"
say $=; p= 0; do until p==0; p= pos(B, A, p+1)
if p\==0 then $= $',' p
end /*until*/
$= space( strip($, 'L', ",") ) /*elide extra blanks and leading comma.*/
- = words($) /*obtain number of words in $ string.*/
if #==0 then say "string A doesn't contain string B"
else say 'string A contains string B ' # " time"left('s', #>1),
"(at position"left('s', #>1) $")" /*stick a fork in it, we're all done. */</lang>
- output when the following is specified (the five Marx brothers): Chico_Harpo_Groucho_Zeppo_Gummo p
string A = Chico_Harpo_Groucho_Zeppo_Gummo string B = p ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ string A doesn't start with string B string A contains string B (starting in position 10) string A doesn't end with string B string A contains string B 3 times (at positions 10, 23, 24)
- output when the following is specified: Chico_Harpo_Groucho_Zeppo_Gummo Z
string A = Chico_Harpo_Groucho_Zeppo_Gummo string B = Z ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ string A doesn't start with string B string A contains string B (starting in position 21) string A doesn't end with string B string A contains string B 1 time (at position 21)
- output when the following is specified: Chico_Harpo_Groucho_Zeppo_Gummo Chi
string A = Chico_Harpo_Groucho_Zeppo_Gummo string B = Chi ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ string A starts with string B string A contains string B (starting in position 1) string A doesn't end with string B string A contains string B 1 time (at position 1)
- output when the following is specified: Chico_Harpo_Groucho_Zeppo_Gummo mmo
string A = Chico_Harpo_Groucho_Zeppo_Gummo string B = mmo ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ string A doesn't start with string B string A contains string B (starting in position 29) string A ends with string B string A contains string B 1 time (at position 29)
Ring
<lang ring> aString = "Welcome to the Ring Programming Language" bString = "Ring" bStringIndex = substr(aString,bString) if bStringIndex > 0 see "" + bStringIndex + " : " + bString ok </lang>
Ruby
<lang ruby>p 'abcd'.start_with?('ab') #returns true p 'abcd'.end_with?('ab') #returns false p 'abab'.include?('bb') #returns false p 'abab'.include?('ab') #returns true p 'abab'['bb'] #returns nil p 'abab'['ab'] #returns "ab" p 'abab'.index('bb') #returns nil p 'abab'.index('ab') #returns 0 p 'abab'.index('ab', 1) #returns 2 p 'abab'.rindex('ab') #returns 2</lang>
Run BASIC
<lang runbasic>s1$ = "abc def ghi klmnop" s2$ = "abc" ' begins with s3$ = "ef" ' is in the string s4$ = "nop" ' ends with
sn2$ = "abcx" ' not begins with sn3$ = "efx" ' not in the string sn4$ = "nopx" ' not ends with
if left$(s1$,len(s2$)) <> s2$ then a$ = "Not " print "String:";s1$;" does ";a$;"begin with:";s2$
if instr(s1$,s3$) = 0 then a$ = "Not " print "String:";s1$;" does ";a$;"contain:";s3$
if mid$(s1$,len(s1$) + 1 - len(s4$),len(s4$)) <> s4$ then a$ = "Not " print "String:";s1$;" does ";a$;"end with:";s4$
' ----------- not ----------------------------- print if left$(s1$,len(sn2$)) <> sn2$ then a$ = "Not " print "String:";s1$;" does ";a$;"begin with:";sn2$
if instr(s1$,sn3$) = 0 then a$ = "Not " print "String:";s1$;" does ";a$;"contain:";sn3$
if mid$(s1$,len(s1$) + 1 - len(sn4$),len(sn4$)) <> sn4$ then a$ = "Not " print "String:";s1$;" does ";a$;"end with:";sn4$</lang>
- Output:
String:abc def ghi klmnop does begin with:abc String:abc def ghi klmnop does contain:ef String:abc def ghi klmnop does end with:nop String:abc def ghi klmnop does Not begin with:abcx String:abc def ghi klmnop does Not contain:efx String:abc def ghi klmnop does Not end with:nopx
Rust
<lang rust>fn print_match(possible_match: Option<usize>) {
match possible_match {
Some(match_pos) => println!("Found match at pos {}", match_pos),
None => println!("Did not find any matches")
}
}
fn main() {
let s1 = "abcd"; let s2 = "abab"; let s3 = "ab"; // Determining if the first string starts with second string assert!(s1.starts_with(s3)); // Determining if the first string contains the second string at any location assert!(s1.contains(s3)); // Print the location of the match print_match(s1.find(s3)); // Found match at pos 0 print_match(s1.find(s2)); // Did not find any matches // Determining if the first string ends with the second string assert!(s2.ends_with(s3));
}</lang>
<lang rust> fn main(){
let hello = String::from("Hello world");
println!(" Start with \"he\" {} \n Ends with \"rd\" {}\n Contains \"wi\" {}",
hello.starts_with("He"),
hello.ends_with("ld"),
hello.contains("wi"));
}</lang>
- Output:
Start with "he" true Ends with "ld" true Contains "wi" false
Scala
<lang scala>"abcd".startsWith("ab") //returns true "abcd".endsWith("zn") //returns false "abab".contains("bb") //returns false "abab".contains("ab") //returns true
var loc="abab".indexOf("bb") //returns -1 loc = "abab".indexOf("ab") //returns 0 loc = "abab".indexOf("ab", loc+1) //returns 2</lang>
Seed7
<lang seed7>$ include "seed7_05.s7i";
const proc: main is func
local
var integer: position is 0;
begin
writeln(startsWith("abcd", "ab")); # write TRUE
writeln(endsWith("abcd", "zn")); # write FALSE
writeln(pos("abab", "bb") <> 0); # write FALSE
writeln(pos("abab", "ab") <> 0); # write TRUE
writeln(pos("abab", "bb")); # write 0
position := pos("abab", "ab");
writeln(position); # position is 1
position := pos("abab", "ab", succ(position));
writeln(position); # position is 3
end func;</lang>
- Output:
TRUE FALSE FALSE TRUE 0 1 3
Sidef
<lang ruby>var first = "abc-abcdef-abcd"; var second = "abc";
say first.begins_with(second); #=> true say first.contains(second); #=> true say first.ends_with(second); #=> false
- Get and print the location of the match
say first.index(second); #=> 0
- Find multiple occurrences of a string
var pos = -1; while (pos = first.index(second, pos+1) != -1) {
say "Match at pos: #{pos}";
}</lang>
Smalltalk
<lang smalltalk>a startsWith: b a includesSubCollection: b. "inherited from superclass" a includesString: b. "the same, but more readable" a endsWith: b a indexOfSubCollection: b "inherited" a indexOfSubCollection: b startingAt: pos "inherited" a indexOfString: b a indexOfStringStartingAt: b </lang>
SNOBOL4
<lang SNOBOL4> s1 = 'abcdabefgab'
s2 = 'ab'
s3 = 'xy'
OUTPUT = ?(s1 ? POS(0) s2) "1. " s2 " begins " s1
OUTPUT = ?(s1 ? POS(0) s3) "1. " s3 " begins " s1 ;# fails
n = 0
again s1 POS(n) ARB s2 @a :F(p3)
OUTPUT = "2. " s2 " found at position "
+ a - SIZE(s2) " in " s1
n = a :(again)
p3 OUTPUT = ?(s1 ? s2 RPOS(0)) "3. " s2 " ends " s1 END</lang>
- Output:
1. ab begins abcdabefgab 2. ab found at position 0 in abcdabefgab 2. ab found at position 4 in abcdabefgab 2. ab found at position 9 in abcdabefgab 3. ab ends abcdabefgab
Standard ML
<lang sml>String.isPrefix "ab" "abcd"; (* returns true *) String.isSuffix "zn" "abcd"; (* returns false *) String.isSubstring "bb" "abab"; (* returns false *) String.isSubstring "ab" "abab"; (* returns true *)
- 2 (Substring.base (#2 (Substring.position "bb" (Substring.full "abab")))); (* returns 4 *)
val loc = #2 (Substring.base (#2 (Substring.position "ab" (Substring.full "abab")))); (* returns 0 *) val loc' = #2 (Substring.base (#2 (Substring.position "ab" (Substring.extract ("abab", loc+1, NONE))))); (* returns 2 *)</lang>
Swift
<lang swift>var str = "Hello, playground" str.hasPrefix("Hell") //True str.hasPrefix("hell") //False
str.containsString("llo") //True str.containsString("xxoo") //False
str.hasSuffix("playground") //True str.hasSuffix("world") //False</lang>
Tailspin
This assumes the string to be found does not contain any regex special characters, otherwise we should work with composers (parsers) see below. <lang tailspin> templates find&{s:}
when <'$s;.*'> do '$; starts with $s;' ! when <'.*$s;'> do '$; ends with $s;' ! when <'.*$s;.*'> do '$; contains $s;' ! otherwise '$s; cannot be found in $;' !
end find
'abcd' -> find&{s:'ab'} -> !OUT::write ' ' -> !OUT::write 'abcd' -> find&{s:'cd'} -> !OUT::write ' ' -> !OUT::write 'abcd' -> find&{s:'bc'} -> !OUT::write ' ' -> !OUT::write 'abcd' -> find&{s:'e'} -> !OUT::write </lang>
- Output:
abcd starts with ab abcd ends with cd abcd contains bc e cannot be found in abcd
Working with composers and literal matchers to be able to handle any string. <lang tailspin> composer startsWith&{s:}
@: 0; (<='$s;'>? -> @:1; <'.*'>) $@
end startsWith
composer endsWith&{s:}
@: 0; (<ends|'.*'>) $@ rule ends: (<'.'>* <='$s;'> -> @:1;)
end endsWith
composer contains&{s:}
@: 0; (<~='$s;'>? <='$s;'>? -> @:1; <'.*'>) $@
end contains
templates find&{s:}
when <?($ -> startsWith&{s:$s} <=1>)> do '$; starts with $s;' !
when <?($ -> endsWith&{s:$s} <=1>)> do '$; ends with $s;' !
when <?($ -> contains&{s:$s} <=1>)> do '$; contains $s;' !
otherwise '$s; cannot be found in $;' !
end find
'abcd' -> find&{s:'ab'} -> !OUT::write ' ' -> !OUT::write 'abcd' -> find&{s:'cd'} -> !OUT::write ' ' -> !OUT::write 'abcd' -> find&{s:'bc'} -> !OUT::write ' ' -> !OUT::write 'abcd' -> find&{s:'e'} -> !OUT::write ' ' -> !OUT::write 'banana' -> find&{s:'na'} -> !OUT::write </lang>
- Output:
abcd starts with ab abcd ends with cd abcd contains bc e cannot be found in abcd banana ends with na
In tailspin we don't manipulate strings by character indices but we can still work out the second part. String characters can be streamed and captured in an array, although we prefer to compare in strings, here with a composer (parser). This has also been crafted to work with strings containing special regex characters by using literal equality. <lang tailspin> composer index&{s:}
@index: 0; [<match>*] rule match: ([<~='$s;'>? ...] -> @: $@ + 1 + $::length;) <'.'>? -> $@
end index
'ba is found in positions $:'banana' -> index&{s:'ba'}; in banana' -> !OUT::write ' ' -> !OUT::write 'ana is found in positions $:'banana' -> index&{s:'ana'}; in banana' -> !OUT::write ' ' -> !OUT::write 'c is found in positions $:'banana' -> index&{s:'c'}; in banana' -> !OUT::write </lang>
- Output:
ba is found in positions [1] in banana ana is found in positions [2, 4] in banana c is found in positions [] in banana
Tcl
In this code, we are looking in various ways for the string in the variable needle in the string in the variable haystack. <lang tcl>set isPrefix [string equal -length [string length $needle] $haystack $needle] set isContained [expr {[string first $needle $haystack] >= 0}] set isSuffix [string equal $needle [string range $haystack end-[expr {[string length $needle]-1}] end]]</lang>
Of course, in the cases where the needle is a glob-safe string (i.e., doesn't have any of the characters “*?[\” in), this can be written far more conveniently: <lang tcl>set isPrefix [string match $needle* $haystack] set isContained [string match *$needle* $haystack] set isSuffix [string match *$needle $haystack]</lang>
Another powerful technique is to use the regular expression engine in literal string mode:
<lang tcl>set isContained [regexp ***=$needle $haystack]</lang>
This can be extended by getting the regexp to return the locations of the matches, enabling the other forms of match to be done:
<lang tcl>set matchLocations [regexp -indices -all -inline ***=$needle $haystack]
- Each match location is a pair, being the index into the string where the needle started
- to match and the index where the needle finished matching
set isContained [expr {[llength $matchLocations] > 0}] set isPrefix [expr {[lindex $matchLocations 0 0] == 0}] set isSuffix [expr {[lindex $matchLocations end 1] == [string length $haystack]-1}] set firstMatchStart [lindex $matchLocations 0 0] puts "Found \"$needle\" in \"$haystack\" at $firstMatchStart" foreach location $matchLocations {
puts "needle matched at index [lindex $location 0]"
}</lang>
TUSCRIPT
<lang tuscript> $$ MODE TUSCRIPT ASK "string1", string1="" ASK "string2", string2=""
IF (string1.sw.string2) THEN PRINT string1," starts with ",string2 ELSE PRINT string1," not starts with ",string2 ENDIF SET beg=STRING (string1,string2,0,0,0,end) IF (beg!=0) THEN PRINT string1," contains ",string2 PRINT " starting in position ",beg PRINT " ending in position ",end ELSE PRINT string1," not contains ",string2 ENDIF
IF (string1.ew.string2) THEN PRINT string1," ends with ",string2 ELSE PRINT string1," not ends with ",string2 ENDIF </lang>
- Output:
string1 >Rosetta Code string2 >Code Rosetta Code not starts with Code Rosetta Code contains Code starting in position 9 ending in position 13 Rosetta Code ends with Code
TXR
TXR Lisp
<lang txrlisp>(tree-case *args*
((big small)
(cond
((< (length big) (length small))
(put-line `@big is shorter than @small`))
((str= big small)
(put-line `@big and @small are equal`))
((starts-with small big)
(put-line `@small is a prefix of @big`))
((ends-with small big)
(put-line `@small is a suffix of @big`))
(t (iflet ((pos (search-str big small)))
(put-line `@small occurs in @big at position @pos`)
(put-line `@small does not occur in @big`)))))
(otherwise
(put-line `usage: @(ldiff *full-args* *args*) <bigstring> <smallstring>`)))</lang>
- Output:
$ txr cmatch2.tl x usage: txr cmatch2.tl <bigstring> <smallstring> $ txr cmatch2.tl x y z usage: txr cmatch2.tl <bigstring> <smallstring> $ txr cmatch2.tl catalog cat cat is a prefix of catalog $ txr cmatch2.tl catalog log log is a suffix of catalog $ txr cmatch2.tl catalog at at occurs in catalog at position 1 $ txr cmatch2.tl catalog catalogue catalog is shorter than catalogue $ txr cmatch2.tl catalog catalog catalog and catalog are equal $ txr cmatch2.tl catalog dog dog does not occur in catalog
Pattern Language
<lang txr>@line @(cases) @ line @ (output) second line is the same as first line @ (end) @(or) @ (skip)@line @ (output) first line is a suffix of the second line @ (end) @(or) @ line@(skip) @ (output) first line is a suffix of the second line @ (end) @(or) @ prefix@line@(skip) @ (output) first line is embedded in the second line at position @(length prefix) @ (end) @(or) @ (output) first line is not found in the second line @ (end) @(end)</lang>
- Output:
$ txr cmatch.txr - 123 01234 first line is embedded in the second line at position 1 $ txr cmatch.txr - 123 0123 first line is a suffix of the second line
Vala
<lang vala>void main() {
var text = "一二三四五六七八九十"; var starts = "一二"; var ends = "九十"; var contains = "五六"; var not_contain = "百"; stdout.printf(@"text: $text\n\n", ); stdout.printf(@"starts with $starts: $(text.has_prefix(starts))\n"); stdout.printf(@"ends with $ends: $(text.has_suffix(ends))\n"); stdout.printf(@"starts with $starts: $(text.has_suffix(starts))\n"); stdout.printf(@"contains $contains: $(contains in text)\n"); stdout.printf(@"contains $not_contain: $(contains in text)\n");
}</lang>
- Output:
text: 一二三四五六七八九十 starts with 一二: true ends with 九十: true starts with 一二: false contains 五六: true contains 百: false
VBA
<lang vb>Public Sub string_matching()
word = "the" '-- (also try this with "th"/"he")
sentence = "the last thing the man said was the"
'-- sentence = "thelastthingthemansaidwasthe" '-- (practically the same results)
'-- A common, but potentially inefficient idiom for checking for a substring at the start is:
If InStr(1, sentence, word) = 1 Then
Debug.Print "yes(1)"
End If
'-- A more efficient method is to test the appropriate slice
If Len(sentence) >= Len(word) _
And Mid(sentence, 1, Len(word)) = word Then
Debug.Print "yes(2)"
End If
'-- Which is almost identical to checking for a word at the end
If Len(sentence) >= Len(word) _
And Mid(sentence, Len(sentence) - Len(word) + 1, Len(word)) = word Then
Debug.Print "yes(3)"
End If
'-- Or sometimes you will see this, a tiny bit more efficient:
If Len(sentence) >= Len(word) _
And InStr(Len(sentence) - Len(word) + 1, sentence, word) Then
Debug.Print "yes(4)"
End If
'-- Finding all occurences is a snap:
r = InStr(1, sentence, word)
Do While r <> 0
Debug.Print r
r = InStr(r + 1, sentence, word)
Loop
End Sub</lang>
- Output:
yes(1) yes(2) yes(3) yes(4) 1 16 33
VBScript
<lang vb>Function StartsWith(s1,s2) StartsWith = False If Left(s1,Len(s2)) = s2 Then StartsWith = True End If End Function
Function Contains(s1,s2) Contains = False If InStr(1,s1,s2) Then Contains = True & " at positions " j = 1 Do Until InStr(j,s1,s2) = False Contains = Contains & InStr(j,s1,s2) & ", " If j = 1 Then If Len(s2) = 1 Then j = j + InStr(j,s1,s2) Else j = j + (InStr(j,s1,s2) + (Len(s2) - 1)) End If Else If Len(s2) = 1 Then j = j + ((InStr(j,s1,s2) - j) + 1) Else j = j + ((InStr(j,s1,s2) - j) + (Len(s2) - 1)) End If End If Loop End If End Function
Function EndsWith(s1,s2) EndsWith = False If Right(s1,Len(s2)) = s2 Then EndsWith = True End If End Function
WScript.StdOut.Write "Starts with test, 'foo' in 'foobar': " & StartsWith("foobar","foo") WScript.StdOut.WriteLine WScript.StdOut.Write "Contains test, 'o' in 'fooooobar': " & Contains("fooooobar","o") WScript.StdOut.WriteLine WScript.StdOut.Write "Ends with test, 'bar' in 'foobar': " & EndsWith("foobar","bar")</lang>
- Output:
Starts with test, 'foo' in 'foobar': True Contains test, 'o' in 'fooooobar': True at positions 2, 3, 4, 5, 6, Ends with test, 'bar' in 'foobar': True
Visual Basic
works the same as in VBA, see String_matching#VBA
Wren
<lang ecmascript>var s = "abracadabra" var t = "abra" var u = "ra" var v = "cad" System.print("'%(s)' starts with '%(t)' is %(s.startsWith(t))") var indices = [] var start = 0 while (true) {
var ix = s.indexOf(u, start)
if (ix >= 0) {
indices.add(ix)
start = ix + u.count
if (start >= s.count) break
} else break
} var contained = indices.count > 0 System.print("'%(s)' contains '%(u)' is %(contained) %(contained ? "at indices %(indices)" : "")") System.print("'%(s)' ends with '%(v)' is %(s.endsWith(v))")</lang>
- Output:
'abracadabra' starts with 'abra' is true 'abracadabra' contains 'ra' is true at indices [2, 9] 'abracadabra' ends with 'cad' is false
XPL0
<lang XPL0>include c:\cxpl\codes; \intrinsic 'code' declarations string 0; \use zero-terminated strings
func StrLen(A); \Return number of characters in a string char A; int I; for I:= 0 to -1>>1-1 do
if A(I) = 0 then return I;
func StrFind(A, B); \Search for string B in string A \Returns index of first occurrence of string B in A, or -1 if B is not found char A, B; \strings to be compared int LA, LB, I, J; [LA:= StrLen(A);
LB:= StrLen(B);
for I:= 0 to LA-LB do
[for J:= 0 to LB-1 do
if B(J) # A(J+I) then J:= LB+1;
if J = LB then return I; \found
];
return -1; ];
char Str; int I, J; [Str:= "pack my box with"; \ 0123456789012345 Text(0, if StrFind(Str, "pack") = 0 then "yes" else "no"); CrLf(0); \1. Text(0, if StrFind(Str, "ack") = 0 then "yes" else "no"); CrLf(0); I:= StrFind(Str, "x w"); Text(0, if I >= 0 then "yes" else "no"); \2. Text(0, ", at offset "); IntOut(0, I); CrLf(0); I:= 0; J:= 0; \offsets of space characters loop [I:= StrFind(Str+J, " ");
if I < 0 then quit;
IntOut(0, I+J); ChOut(0, ^ );
J:= J+I+1;
];
CrLf(0); Text(0, if StrFind(Str, "X w") >= 0 then "yes" else "no"); CrLf(0); Text(0, if StrFind(Str, "with") = StrLen(Str)-StrLen("with") then "yes" else "no"); CrLf(0); \3. Text(0, if StrFind(Str, "x w" ) = StrLen(Str)-StrLen("x w" ) then "yes" else "no"); CrLf(0); ]</lang>
- Output:
yes no yes, at offset 10 4 7 11 no yes no
XProfan
<lang XProfan> // XProfan can use StringParts, so the results here // are the comma separated positions of the parts or 0 Proc Contains
Parameters string content, part
var string results = "0"
var long posi = 1
posi = InStr(part,content,posi)
if posi <> 0
results = str$(posi)
repeat
posi = InStr(part,content,posi+1)
case posi <> 0 : results = results + "," + str$(posi)
until posi == 0
endif
Return results
EndProc
Proc StartsWith
Parameters string content, part Return if(Left$(content,Len(part)) == part, 1, 0)
EndProc
Proc EndsWith
Parameters string content, part Return if(Right$(content,Len(part)) == part, 1, 0) 'Return if(Left$(content,Len(content)-Len(part)+1) == part, 1, 0)
EndProc
var string theContent = "foobar" var string thePart = "foo" Print "Starts with: " Print " ("+thePart+" in "+theContent+") "+if(StartsWith(theContent,thePart),"Yes","No") thePart = "back" Print " ("+thePart+" in "+theContent+") "+if(StartsWith(theContent,thePart),"Yes","No")
theContent = "foooooobar" Print "Contains: " Print " ("+thePart+" in "+theContent+") "+ Contains(theContent,thePart) thePart = "o" Print " ("+thePart+" in "+theContent+") "+ Contains(theContent,thePart)
theContent = "foobar" thePart = "back" Print "Ends with: " Print " ("+thePart+" in "+theContent+") "+if(EndsWith(theContent,thePart),"Yes","No") thePart = "bar" Print " ("+thePart+" in "+theContent+") "+if(EndsWith(theContent,thePart),"Yes","No")
waitkey end</lang>
- Output:
Starts with: (foo in foobar) Yes (back in foobar) No Contains: (back in foooooobar) 0 (o in foooooobar) 2,3,4,5,6,7 Ends with: (back in foobar) No (bar in foobar) Yes
Yabasic
<lang Yabasic> cadena1$ = "qwertyuiop"
//Determinar si la primera cadena comienza con la segunda cadena cadena2$ = "qwerty" if left$(cadena1$, len(cadena2$)) = cadena2$ then
print "'", cadena1$, "' comienza con '", cadena2$, "'"
else
print "'", cadena1$, "' no comienza con '", cadena2$, "'"
end if
//Determinar si la primera cadena contiene la segunda cadena en cualquier //ubicación imprima la ubicación de la coincidencia para la parte 2 cadena2$ = "wert" posic = instr(cadena1$, cadena2$) if posic then
print "'", cadena1$, "' contiene '", cadena2$, "' en la posicion ", posic
else
print "'", cadena1$, "' no contiene '", cadena2$, "'"
end if
//Determinar si la primera cadena termina con la segunda cadena cadena2$ = "random garbage" if right$(cadena1$, len(cadena2$)) = cadena2$ then
print "'", cadena1$, "' termina con '", cadena2$, "'"
else
print "'", cadena1$, "' no termina con '", cadena2$, "'"
end if end </lang>
- Output:
'qwertyuiop' comienza con 'qwerty' 'qwertyuiop' contiene 'wert' en la posicion 2 'qwertyuiop' no termina con 'random garbage'
zkl
<lang zkl>fcn f(text,p){ if(text.find(p)==0)println("Yep") else println("Nope") } f("foobar","foo") //--> Yep f("foobar","bar") //--> Nope</lang> <lang zkl>fcn f(text,p){ if(Void!=(n:=text.find(p)))println("Contained @",n) else println("Nope") } f("foobar","ob") //--> Contained @2 f("foobar","food") //--> Nope</lang> <lang zkl>fcn f(text,p){
if( Void!=(n:=text.rfind(p)) and n+p.len()==text.len() )
println("tail gunner") else println("Nope")
} f("foobar","r"); f("foobar","ar"); //--> tail gunners f("foobar","ob"); //--> Nope f("foobarfoobar","bar"); //--> tail gunner</lang>
- Programming Tasks
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