String matching: Difference between revisions
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=={{header|LabVIEW}}== |
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These images solve the task's requirements in order.<br/>{{VI snippet}}<br/> |
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[[File:LabVIEW_Character_matching_1.png]]<br/> |
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[[File:LabVIEW_Character_matching_2.png]]<br/> |
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[[File:LabVIEW_Character_matching_3.png]] |
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=={{header|Liberty BASIC}}== |
=={{header|Liberty BASIC}}== |
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<lang lb>'1---Determining if the first string starts with second string |
<lang lb>'1---Determining if the first string starts with second string |
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end if |
end if |
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</lang> |
</lang> |
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=={{header|Logo}}== |
=={{header|Logo}}== |
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<lang logo>to starts.with? :sub :thing |
<lang logo>to starts.with? :sub :thing |
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Revision as of 21:28, 21 January 2012
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
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 for part 2
- Handle multiple occurrences of a string for part 2.
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> Sample output:
'abcd' starts with 'ab' 'abab' ends with 'ab' 'ab' first appears in 'abcd' at 1 'ab' appears in 'abab' 2 times
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
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>
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'
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)
C
Case sensitive matching: <lang C>#include <string.h>
- include <stdio.h>
int startsWith(char* container, char* target) {
size_t clen = strlen(container), tlen = strlen(target); if (clen < tlen) return 0; return strncmp(container, target, tlen) == 0;
}
int endsWith(char* container, 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(char* container, 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(char *a, 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(char *a, 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 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>
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>
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>
D
<lang d>import std.stdio, std.algorithm ; void main() {
writeln("abcd".startsWith("ab")) ; // true
writeln("abcd".endsWith("zn")) ; // false
writeln("abab".find("bb")) ; // empty array (no match)
writeln("abcd".find("bc")) ; // "bcd" (substring start at match)
writeln("abab".indexOf("bb")) ; // -1 (no match)
writeln("abab".indexOf("ba")) ; // 1 (index of 1st match)
// above function from algorithm module not only work for string but
// also other array and range
writeln([1,2,3].indexOf(3)) ; // 2
writeln([1,2,3].indexOf([2,3])) ; // 1
}</lang>
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>
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>
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'
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'
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>
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
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 = map fst $ filter (isPrefixOf a . snd) $ zip [0..] $ 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>
Sample 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>
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.
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>
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.
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>
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>
Mathematica
<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}}
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>
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>
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>
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)
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
<lang perl># the first four examples use regular expressions, so make sure to escape any special regex characters in the substring "abcd" =~ /^ab/ #returns true "abcd" =~ /zn$/ #returns false "abab" =~ /bb/ #returns false "abab" =~ /ab/ #returns true my $loc = index("abab", "bb") #returns -1 $loc = index("abab", "ab") #returns 0 $loc = index("abab", "ab", $loc+1) #returns 2</lang>
Perl 6
<lang perl6>my @subs = (
# Regex-based:
sub R_contains ( Str $_, Str $s2 ) { ? m/ $s2 / },
sub R_starts_with ( Str $_, Str $s2 ) { ? m/ ^ $s2 / },
sub R_ends_with ( Str $_, Str $s2 ) { ? m/ $s2 $ / },
# Index-based:
sub I_contains ( Str $_, Str $s2 ) { .index( $s2)\ .defined },
sub I_starts_with ( Str $_, Str $s2 ) { my $m = .index( $s2); $m.defined and $m == 0 },
sub I_ends_with ( Str $_, Str $s2 ) { my $m = .rindex($s2); $m.defined and $m == .chars - $s2.chars },
# Substr-based:
sub S_starts_with ( Str $_, Str $s2 ) { .substr(0, $s2.chars) eq $s2 },
sub S_ends_with ( Str $_, Str $s2 ) { .substr( -$s2.chars) eq $s2 },
# Optional tasks:
sub R_find ( Str $_, Str $s2 ) { $/.from if /$s2/ },
sub R_find_all ( Str $_, Str $s2 ) {
my @p = .match: /$s2/, :g;
@p».from if @p;
},
);
my $str1 = 'abcbcbcd'; my @str2s = < ab bc cd zz >;
say "'$str1' vs:".fmt('%15s '), @str2s.fmt('%-15s'); for [1, 4, 6], [2, 5, 7], [0, 3], [8, 9] {
say;
for @subs[.list] -> $sub {
say "{$sub.name}:".fmt('%15s '),
@str2s.map({ ~$sub.($str1, $_) }).fmt('%-15s');
}
}</lang>
Output:
'abcbcbcd' vs: ab bc cd zz
R_starts_with: Bool::True Bool::False Bool::False Bool::False
I_starts_with: Bool::True Bool::False Bool::False Bool::False
S_starts_with: Bool::True Bool::False Bool::False Bool::False
R_ends_with: Bool::False Bool::False Bool::True Bool::False
I_ends_with: Bool::False Bool::False Bool::True Bool::False
S_ends_with: Bool::False Bool::False Bool::True Bool::False
R_contains: Bool::True Bool::True Bool::True Bool::False
I_contains: Bool::True Bool::True Bool::True Bool::False
R_find: 0 1 6 Nil()
R_find_all: 0 1 3 5 6 Nil()
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>
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> Sample output:
1 0 0 1 3 7 0 0 1
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
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>
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 of using plurals in the messages. <lang rexx> /*REXX program to show some basic character string testing. */
parse arg a b
say 'string A=' a say 'string B=' b say
if left(A,length(b))==b then say 'string A starts with string B'
else say "string A doesn't start with string B"
say
p=pos(b,a) if p\==0 then say 'string A contains string B (starting in position' p")"
else say "string A doesn't contains string B"
say
if right(A,length(b))==b then say 'string A ends with string B'
else say "string A doesn't end with string B"
say
Ps= p=0
do forever until p==0 p=pos(b,a,p+1) if p\==0 then Ps=Ps',' p end
Ps=space(strip(Ps,'L',",")) times=words(Ps) if times\==0 then say 'string A contains string B',
times 'time'left('s',times>1),
"(at position"left('s',times>1) Ps')'
else say "string A doesn't contains string B"
</lang>
Output when the following is specified (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)
Ruby
<lang ruby>'abcd'.start_with?('ab') #returns true 'abcd'.end_with?('zn') #returns false 'abab'.include?('bb') #returns false 'abab'.include?('ab') #returns true 'abab'.index('bb') #returns -1 'abab'.index('ab') #returns 0 'abab'.index('ab', 1) #returns 2</lang>
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
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>
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
- Programming Tasks
- String manipulation
- Basic Data Operations
- Ada
- ALGOL 68
- AutoHotkey
- BASIC
- BBC BASIC
- C
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- TUSCRIPT