Strip whitespace from a string/Top and tail
You are encouraged to solve this task according to the task description, using any language you may know.
- Task
Demonstrate how to strip leading and trailing whitespace from a string.
The solution should demonstrate how to achieve the following three results:
- String with leading whitespace removed
- String with trailing whitespace removed
- String with both leading and trailing whitespace removed
For the purposes of this task whitespace includes non printable characters such as the space character, the tab character, and other such characters that have no corresponding graphical representation.
- 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
V s = " \t \r \n String with spaces \t \r \n "
print(s.ltrim((‘ ’, "\t", "\r", "\n")).len)
print(s.rtrim((‘ ’, "\t", "\r", "\n")).len)
print(s.trim((‘ ’, "\t", "\r", "\n")).len)
- Output:
29 25 18
AArch64 Assembly
/* ARM assembly AARCH64 Raspberry PI 3B */
/* program Strip whitespace from a string */
/*******************************************/
/* Constantes */
/*******************************************/
/* for this file see task include a file in language AArch64 assembly*/
.include "../includeConstantesARM64.inc"
.equ BUFFERSIZE, 200
/*******************************************/
/* macros */
/*******************************************/
//.include "../../ficmacros64.inc" // for developper debugging
/*********************************/
/* Initialized data */
/*********************************/
.data
szMessDebutPgm: .asciz "Program 64 bits start. \n"
szCarriageReturn: .asciz "\n"
szMessFinOK: .asciz "Program normal end. \n"
szMessBufferError: .asciz "Error : Buffer too small !!\n"
szEndString: .asciz "<<<<"
szString1: .asciz " apples, pears # and bananas"
szString2: .asciz "apples, pears ; and bananas "
.equ LGSTRING2, . - szString2
szString3: .asciz " \tapples, pears ; and bananas "
.align 4
/*********************************/
/* UnInitialized data */
/*********************************/
.bss
sBuffer: .skip BUFFERSIZE
.align 4
/*********************************/
/* code section */
/*********************************/
.text
.global main
main:
ldr x0,qAdrszMessDebutPgm
bl affichageMess // start message
ldr x0,qAdrszString1
ldr x1,qAdrsBuffer
mov x2,#BUFFERSIZE
bl stripTail
cmp x0,#-1
beq 1f
ldr x0,qAdrsBuffer
bl affichageMess
ldr x0,qAdrszCarriageReturn
bl affichageMess
1:
ldr x0,qAdrszString2
mov x1,#LGSTRING2
ldr x2,qAdrsBuffer
mov x3,#BUFFERSIZE
bl stripTop
cmp x0,#-1
beq 2f
ldr x0,qAdrsBuffer
bl affichageMess
ldr x0,qAdrszEndString
bl affichageMess
ldr x0,qAdrszCarriageReturn
bl affichageMess
2:
ldr x0,qAdrszString3
mov x1,#LGSTRING2
ldr x2,qAdrsBuffer
mov x3,#BUFFERSIZE
bl stripSpaces
cmp x0,#-1
beq 100f
ldr x0,qAdrsBuffer
bl affichageMess
ldr x0,qAdrszEndString
bl affichageMess
ldr x0,qAdrszCarriageReturn
bl affichageMess
ldr x0,qAdrszMessFinOK
bl affichageMess
100:
mov x8,EXIT
svc #0 // system call
qAdrszMessDebutPgm: .quad szMessDebutPgm
qAdrszMessFinOK: .quad szMessFinOK
qAdrszCarriageReturn: .quad szCarriageReturn
qAdrszMessBufferError: .quad szMessBufferError
qAdrsBuffer: .quad sBuffer
qAdrszEndString: .quad szEndString
qAdrszString1: .quad szString1
qAdrszString2: .quad szString2
qAdrszString3: .quad szString3
/******************************************************************/
/* strip leading space */
/******************************************************************/
/* x0 contains string address */
/* x1 contains buffer address */
/* x2 contains buffer length maxi */
/* x0 returns buffer length */
stripTail:
stp x1,lr,[sp,-16]!
stp x2,x3,[sp,-16]!
stp x4,x5,[sp,-16]!
stp x6,x7,[sp,-16]!
mov x3,#0 // indice string
mov x4,#0 // indice buffer write
mov x6,#0 // spaces top
1:
ldrb w5,[x0,x3]
cmp x5,#0 // end string
beq 3f
cmp x6,#1 // end spaces
beq 2f
cmp x5,#' ' // space ?
cinc x3,x3,eq // increment indice
beq 1b // and loop
cmp x5,#'\t' // tabulation ?
cinc x3,x3,eq // increment indice
beq 1b
mov x6,#1 // end first spaces
2:
strb w5,[x1,x4] // write byte
add x4,x4,#1
cmp x4,x2 // error ?
bge 99f
add x3,x3,#1
b 1b // loop
3:
strb w5,[x1,x4] // write byte final zero
add x0,x4,#1
b 100f
99: // error
ldr x0,qAdrszMessBufferError
bl affichageMess
mov x0,#-1
100:
ldp x6,x7,[sp],16
ldp x4,x5,[sp],16
ldp x2,x3,[sp],16
ldp x1,lr,[sp],16
ret
/******************************************************************/
/* strip trailing space */
/******************************************************************/
/* x0 contains string address */
/* x1 contains length string
/* x2 contains buffer address */
/* x3 contains buffer length maxi */
/* x0 returns buffer length */
stripTop:
stp x1,lr,[sp,-16]!
stp x2,x3,[sp,-16]!
stp x4,x5,[sp,-16]!
stp x6,x7,[sp,-16]!
mov x4,#0 // indice buffer write
mov x6,#0 // top last spaces
sub x1,x1,#1 // final zero
1:
ldrb w5,[x0,x1] // load last byte
cmp x6,#1 // end spaces?
beq 2f
sub x7,x1,1
cmp x5,#' ' // space ?
csel x1,x7,x1,eq // decrement indice
beq 1b // and loop
cmp x5,#'\t'
csel x1,x7,x1,eq // decrement indice
beq 1b
mov x6,#0 // final zero
add x4,x1,#1 // increment last position not space
cmp x4,x3 // error ?
bge 99f
strb w6,[x2,x4] // write zero final
mov x7,x4 // save length
mov x6,#1 // end last spaces
2: // not space
mov x4,x1 // last position
strb w5,[x2,x4] // write byte
subs x3,x3,#1
bgt 1b // and loop
3:
mov x0,x7
b 100f
99: // error
ldr x0,qAdrszMessBufferError
bl affichageMess
mov x0,#-1
100:
ldp x6,x7,[sp],16
ldp x4,x5,[sp],16
ldp x2,x3,[sp],16
ldp x1,lr,[sp],16 // TODO: a completer
ret
/******************************************************************/
/* strip leading and trailing spaces */
/******************************************************************/
/* x0 contains string address */
/* x1 contains buffer address */
/* x2 contains buffer length maxi */
/* x0 returns buffer length */
stripSpaces:
stp x1,lr,[sp,-16]!
stp x2,x3,[sp,-16]!
stp x4,x5,[sp,-16]!
sub sp,sp,x2 // reserve area on stack
mov x4,x1 // save buffer address
mov x5,x2 // save length
mov x1,sp // address temp buffer
mov x2,x5
bl stripTail // strip leading spaces
cmp x0,#-1 // error ?
beq 100f
mov x1,x0 // new length string
mov x0,sp // temp buffer address
mov x1,x4 // buffer address
mov x2,x5 // maxi length
bl stripTop // stip trailing spaces
100:
add sp,sp,x5 // free area on stack
ldp x4,x5,[sp],16
ldp x2,x3,[sp],16
ldp x1,lr,[sp],16 // TODO: a completer
ret
/***************************************************/
/* ROUTINES INCLUDE */
/***************************************************/
/* for this file see task include a file in language AArch64 assembly*/
.include "../includeARM64.inc"
- Output:
Program 64 bits start. apples, pears # and bananas apples, pears # and bananas<<<< apples, pears # and bananas<<<< Program normal end.
Action!
DEFINE SPACE="32"
DEFINE TAB="127"
DEFINE NEWLINE="155"
BYTE FUNC IsWhitespace(CHAR c)
IF c=SPACE OR c=TAB OR c=NEWLINE THEN
RETURN (1)
FI
RETURN (0)
PROC Strip(CHAR ARRAY src,dst BYTE head,tail)
BYTE i,first,last
first=1
last=src(0)
IF head THEN
WHILE first<=last
DO
IF IsWhitespace(src(first))=0 THEN
EXIT
FI
first==+1
OD
FI
IF tail THEN
WHILE last>=first
DO
IF IsWhitespace(src(last))=0 THEN
EXIT
FI
last==-1
OD
FI
IF first>last THEN
dst(0)=0
ELSE
SCopyS(dst,src,first,last)
FI
RETURN
PROC Main()
CHAR ARRAY src=" Action! ",dst(20)
src(2)=NEWLINE src(13)=TAB
PrintF("Original string:%E""%S""%E%E",src)
Strip(src,dst,1,0)
PrintF("Trim leading whitespaces:%E""%S""%E%E",dst)
Strip(src,dst,0,1)
PrintF("Trim trailing whitespaces:%E""%S""%E%E",dst)
Strip(src,dst,1,1)
PrintF("Trim leading and trailing whitespaces:""%S""%E%E",dst)
RETURN
- Output:
Screenshot from Atari 8-bit computer
Original string: " Action! " Trim leading whitespaces: "Action! " Trim trailing whitespaces: " Action!" Trim leading and trailing whitespaces: "Action!"
Ada
with Ada.Text_IO; use Ada.Text_IO;
with Ada.Strings; use Ada.Strings;
with Ada.Strings.Fixed; use Ada.Strings.Fixed;
procedure StripDemo is
str : String := " Jabberwocky ";
begin
Put_Line ("'" & Trim (str, Left) & "'");
Put_Line ("'" & Trim (str, Right) & "'");
Put_Line ("'" & Trim (str, Both) & "'");
end StripDemo;
- Output:
'Jabberwocky ' ' Jabberwocky' 'Jabberwocky'
ALGOL 68
version 1
# returns "text" with leading non-printing characters removed #
PROC trim leading whitespace = ( STRING text )STRING:
BEGIN
INT pos := LWB text;
WHILE
IF pos > UPB text
THEN
FALSE
ELSE
text[ pos ] <= " "
FI
DO
pos +:= 1
OD;
text[ pos : ]
END; # trim leading whitespace #
# returns "text" with trailing non-printing characters removed #
PROC trim trailing whitespace = ( STRING text )STRING:
BEGIN
INT pos := UPB text;
WHILE
IF pos < LWB text
THEN
FALSE
ELSE
text[ pos ] <= " "
FI
DO
pos -:= 1
OD;
text[ : pos ]
END; # trim trailing whitespace #
# returns "text" with leading and trailing non-printing characters removed #
PROC trim whitespace = ( STRING text )STRING:
BEGIN
trim trailing whitespace( trim leading whitespace( text ) )
END; # trim whitespace #
BEGIN
STRING test = " leading and trailing spaces surrounded this text ";
print( ( "trim leading: """ + trim leading whitespace ( test ) + """", newline ) );
print( ( "trim trailing: """ + trim trailing whitespace( test ) + """", newline ) );
print( ( "trim both: """ + trim whitespace ( test ) + """", newline ) )
END
- Output:
trim leading: "leading and trailing spaces surrounded this text " trim trailing: " leading and trailing spaces surrounded this text" trim both: "leading and trailing spaces surrounded this text"
version 2
A single procedure that trims leading space, trailing space, or both.
#
string_trim
Trim leading and trailing whitespace from string.
@param str A string.
@return A string trimmed of leading and trailing white space.
#
PROC string_trim = (STRING str) STRING: (
INT i := 1, j := 0;
WHILE str[i] = blank DO
i +:= 1
OD;
WHILE str[UPB str - j] = blank DO
j +:= 1
OD;
str[i:UPB str - j]
);
# test # (
IF string_trim(" foobar") /= "foobar" THEN
print(("string_trim(' foobar'): expected 'foobar'; actual: "
+ string_trim(" foobar"), newline)) FI;
IF string_trim("foobar ") /= "foobar" THEN
print(("string_trim('foobar '): expected 'foobar'; actual: "
+ string_trim("foobar "), newline)) FI;
IF string_trim(" foobar ") /= "foobar" THEN
print(("string_trim(' foobar '): expected 'foobar'; actual: "
+ string_trim(" foobar "), newline)) FI
)
Amazing Hopper
Amazing Hopper! Flavour "Jambo".
#include <jambo.h>
Main
Set stack 25
c = "\t\t\n \n Message to triming\t\n \t"
Printnl ("Original Message: [", c,"]")
Set '"\n\n\UL\ENFNatural syntax:\n\n"', then bold off, and underline off
Set '"Right trim: [", c', Do right trim; then set '"]"'
Set '"\nLeft trim: [", c', Do left trim; Set '"]"'
Set '"\nAll trim: [", c', Do trim, now set '"]"' and print with newline
Underline( Bold( "\n\nFormal syntax:\n\n" ))
Printnl ( "Right trim: [", Rtrim(c),\
"]\nLeft trim: [", Ltrim(c),\
"]\nAll trim: [",Trim(c),"]\n" )
End
- Output:
Original Message: [ Message to triming ] Natural syntax: Right trim: [ Message to triming] Left trim: [Message to triming ] All trim: [Message to triming] Formal syntax: Right trim: [ Message to triming] Left trim: [Message to triming ] All trim: [Message to triming]
AppleScript
use framework "Foundation" -- "OS X" Yosemite onwards, for NSRegularExpression
-- STRIP WHITESPACE ----------------------------------------------------------
-- isSpace :: Char -> Bool
on isSpace(c)
((length of c) = 1) and regexTest("\\s", c)
end isSpace
-- stripStart :: Text -> Text
on stripStart(s)
dropWhile(isSpace, s) as text
end stripStart
-- stripEnd :: Text -> Text
on stripEnd(s)
dropWhileEnd(isSpace, s) as text
end stripEnd
-- strip :: Text -> Text
on strip(s)
dropAround(isSpace, s) as text
end strip
-- TEST ----------------------------------------------------------------------
on run
set strText to " \t\t \n \r Much Ado About Nothing \t \n \r "
script arrowed
on |λ|(x)
"-->" & x & "<--"
end |λ|
end script
map(arrowed, [stripStart(strText), stripEnd(strText), strip(strText)])
-- {"-->Much Ado About Nothing
--
-- <--", "-->
--
-- Much Ado About Nothing<--", "-->Much Ado About Nothing<--"}
end run
-- GENERIC FUNCTIONS ---------------------------------------------------------
-- dropAround :: (Char -> Bool) -> [a] -> [a]
on dropAround(p, xs)
dropWhile(p, dropWhileEnd(p, xs))
end dropAround
-- dropWhile :: (a -> Bool) -> [a] -> [a]
on dropWhile(p, xs)
tell mReturn(p)
set lng to length of xs
set i to 1
repeat while i ≤ lng and |λ|(item i of xs)
set i to i + 1
end repeat
end tell
if i ≤ lng then
items i thru lng of xs
else
{}
end if
end dropWhile
-- dropWhileEnd :: (a -> Bool) -> [a] -> [a]
on dropWhileEnd(p, xs)
tell mReturn(p)
set i to length of xs
repeat while i > 0 and |λ|(item i of xs)
set i to i - 1
end repeat
end tell
if i > 0 then
items 1 thru i of xs
else
{}
end if
end dropWhileEnd
-- map :: (a -> b) -> [a] -> [b]
on map(f, xs)
tell mReturn(f)
set lng to length of xs
set lst to {}
repeat with i from 1 to lng
set end of lst to |λ|(item i of xs, i, xs)
end repeat
return lst
end tell
end map
-- Lift 2nd class handler function into 1st class script wrapper
-- mReturn :: Handler -> Script
on mReturn(f)
if class of f is script then
f
else
script
property |λ| : f
end script
end if
end mReturn
-- regexTest :: RegexPattern -> String -> Bool
on regexTest(strRegex, str)
set ca to current application
set oString to ca's NSString's stringWithString:str
((ca's NSRegularExpression's regularExpressionWithPattern:strRegex ¬
options:((ca's NSRegularExpressionAnchorsMatchLines as integer)) ¬
|error|:(missing value))'s firstMatchInString:oString options:0 ¬
range:{location:0, |length|:oString's |length|()}) is not missing value
end regexTest
- Output:
{"-->Much Ado About Nothing
<--", "-->
Much Ado About Nothing<--", "-->Much Ado About Nothing<--"}
ARM Assembly
/* ARM assembly Raspberry PI */
/* program Strip whitespace from a string */
/* REMARK 1 : this program use routines in a include file
see task Include a file language arm assembly
for the routine affichageMess conversion10
see at end of this program the instruction include */
/*******************************************/
/* Constantes */
/*******************************************/
.include "../constantes.inc"
.equ BUFFERSIZE, 200
/*******************************************/
/* macros */
/*******************************************/
//.include "../../ficmacros32.inc" @ for developper debugging
/*********************************/
/* Initialized data */
/*********************************/
.data
szMessDebutPgm: .asciz "Program 32 bits start. \n"
szCarriageReturn: .asciz "\n"
szMessFinOK: .asciz "Program normal end. \n"
szMessBufferError: .asciz "Error : Buffer too small !!\n"
szEndString: .asciz "<<<<"
szString1: .asciz " apples, pears # and bananas"
szString2: .asciz "apples, pears ; and bananas "
.equ LGSTRING2, . - szString2
szString3: .asciz " \tapples, pears ; and bananas "
.align 4
/*********************************/
/* UnInitialized data */
/*********************************/
.bss
sBuffer: .skip BUFFERSIZE
.align 4
/*********************************/
/* code section */
/*********************************/
.text
.global main
main:
ldr r0,iAdrszMessDebutPgm
bl affichageMess @ start message
ldr r0,iAdrszString1
ldr r1,iAdrsBuffer
mov r2,#BUFFERSIZE
bl stripTail
cmp r0,#-1
beq 1f
ldr r0,iAdrsBuffer
bl affichageMess
ldr r0,iAdrszCarriageReturn
bl affichageMess
1:
ldr r0,iAdrszString2
mov r1,#LGSTRING2
ldr r2,iAdrsBuffer
mov r3,#BUFFERSIZE
bl stripTop
cmp r0,#-1
beq 2f
ldr r0,iAdrsBuffer
bl affichageMess
ldr r0,iAdrszEndString
bl affichageMess
ldr r0,iAdrszCarriageReturn
bl affichageMess
2:
ldr r0,iAdrszString3
mov r1,#LGSTRING2
ldr r2,iAdrsBuffer
mov r3,#BUFFERSIZE
bl stripSpaces
cmp r0,#-1
beq 100f
ldr r0,iAdrsBuffer
bl affichageMess
ldr r0,iAdrszEndString
bl affichageMess
ldr r0,iAdrszCarriageReturn
bl affichageMess
ldr r0,iAdrszMessFinOK
bl affichageMess
100:
mov r7,#EXIT @ program end
svc #0 @ system call
iAdrszMessDebutPgm: .int szMessDebutPgm
iAdrszMessFinOK: .int szMessFinOK
iAdrszCarriageReturn: .int szCarriageReturn
iAdrszMessBufferError: .int szMessBufferError
iAdrsBuffer: .int sBuffer
iAdrszEndString: .int szEndString
iAdrszString1: .int szString1
iAdrszString2: .int szString2
iAdrszString3: .int szString3
/******************************************************************/
/* strip leading space */
/******************************************************************/
/* r0 contains string address */
/* r1 contains buffer address */
/* r2 contains buffer length maxi */
/* r0 returns buffer length */
stripTail:
push {r1-r6,lr} @ save registers
mov r3,#0 @ indice string
mov r4,#0 @ indice buffer write
mov r6,#0 @ spaces top
1:
ldrb r5,[r0,r3]
cmp r5,#0 @ end string
beq 3f
cmp r6,#1 @ end spaces
beq 2f
cmp r5,#' ' @ space ?
addeq r3,r3,#1 @ increment indice
beq 1b @ and loop
cmp r5,#'\t' @ tabulation ?
addeq r3,r3,#1
beq 1b
mov r6,#1 @ end first spaces
2:
strb r5,[r1,r4] @ write byte
add r4,r4,#1
cmp r4,r2 @ error ?
bge 99f
add r3,r3,#1
b 1b @ loop
3:
strb r5,[r1,r4] @ write byte final zero
add r0,r4,#1
b 100f
99: @ error
ldr r0,iAdrszMessBufferError
bl affichageMess
mov r0,#-1
100:
pop {r1-r6,pc}
/******************************************************************/
/* strip trailing space */
/******************************************************************/
/* r0 contains string address */
/* r1 contains length string
/* r2 contains buffer address */
/* r3 contains buffer length maxi */
/* r0 returns buffer length */
stripTop:
push {r1-r7,lr} @ save registers
mov r4,#0 @ indice buffer write
mov r6,#0 @ top last spaces
sub r1,r1,#1 @ final zero
1:
ldrb r5,[r0,r1] @ load last byte
cmp r6,#1 @ end spaces?
beq 2f
cmp r5,#' ' @ space ?
subeq r1,r1,#1 @ decrement indice
beq 1b @ and loop
cmp r5,#'\t'
subeq r1,r1,#1
beq 1b
mov r6,#0 @ final zero
add r4,r1,#1 @ increment last position not space
cmp r4,r3 @ error ?
bge 99f
strb r6,[r2,r4] @ write zero final
mov r7,r4 @ save length
mov r6,#1 @ end last spaces
2: @ not space
mov r4,r1 @ last position
strb r5,[r2,r4] @ write byte
subs r3,r3,#1
bgt 1b @ and loop
3:
mov r0,r7
b 100f
99: @ error
ldr r0,iAdrszMessBufferError
bl affichageMess
mov r0,#-1
100:
pop {r1-r7,pc}
/******************************************************************/
/* strip leading and trailing spaces */
/******************************************************************/
/* r0 contains string address */
/* r1 contains buffer address */
/* r2 contains buffer length maxi */
/* r0 returns buffer length */
stripSpaces:
push {r1-r7,lr} @ save registers
sub sp,sp,r2 @ reserve area on stack
mov r4,r1 @ save buffer address
mov r5,r2 @ save length
mov r1,sp @ address temp buffer
mov r2,r5
bl stripTail @ strip leading spaces
cmp r0,#-1 @ error ?
beq 100f
mov r1,r0 @ new length string
mov r0,sp @ temp buffer address
mov r1,r4 @ buffer address
mov r2,r5 @ maxi length
bl stripTop @ stip trailing spaces
100:
add sp,sp,r5 @ free area on stack
pop {r1-r7,pc}
/***************************************************/
/* ROUTINES INCLUDE */
/***************************************************/
.include "../affichage.inc"
- Output:
Program 32 bits start. apples, pears # and bananas apples, pears # and bananas<<<< apples, pears # and bananas<<<< Program normal end.
Arturo
str: " Hello World "
print [pad "strip all:" 15 ">" strip str "<"]
print [pad "strip leading:" 15 ">" strip.start str "<"]
print [pad "strip trailing:" 15 ">" strip.end str "<"]
- Output:
strip all: > Hello World < strip leading: > Hello World < strip trailing: > Hello World <
AutoHotkey
AutoHotkey_L and v2 contain a Trim function
string := " abc "
MsgBox % clipboard := "<" LTrim(string) ">`n<" RTrim(string) ">`n<" . Trim(string) ">"
- Output:
<abc > < abc> <abc>
AWK
- [:graph:] is a POSIX character class for characters that are both printable and visible. The following strips the entire non-[:graph:] character set. A simplified version for the more common task of removing only spaces and tabs follows it.
function trimleft(str ,c, out, arr) {
c = split(str, arr, "")
for ( i = match(str, /[[:graph:]]/); i <= c; i++)
out = out arr[i]
return out
}
function reverse(str ,n, tmp, j, out) {
n = split(str, tmp, "")
for (j = n; j > 0; j--)
out = out tmp[j]
return out
}
function trimright(str) {
return reverse(trimleft(reverse(str)))
}
function trim(str) {
return trimright(trimleft(str))
}
BEGIN {
str = " \x0B\t\r\n \xA0 Hellö \xA0\x0B\t\r\n "
print "string = |" str "|"
print "left = |" trimleft(str) "|"
print "right = |" trimright(str) "|"
print "both = |" trim(str) "|"
}
- Output from 26 May 2015:
string = | ▒ Hellö ▒ | left = |Hellö ▒ | right = | ▒ Hellö| both = |Hellö|
Simplified for removing [:blank:] (spaces and tabs) or [:space:] (for [ \t\r\n\v\f] ). This method does not work using [:graph:]
function trim(str) {
gsub(/^[[:blank:]]+/,"", str) # Remove leading
gsub(/[[:blank:]]+$/,"", str) # Remove trailing
gsub(/^[[:blank:]]+|[[:blank:]]+$/, "", str) # Remove both
return str;
}
BaCon
'---Remove leading whitespace
PRINT CHOP$(" String with spaces "," ",1)
'---Remove trailing whitespace
PRINT CHOP$(" String with spaces "," ",2)
'---Remove both leading and trailing whitespace
PRINT CHOP$(" String with spaces "," ",0)
BASIC
mystring$=ltrim(mystring$) ' remove leading whitespace
mystring$=rtrim(mystring$) ' remove trailing whitespace
mystring$=ltrim(rtrim(mystring$)) ' remove both leading and trailing whitespace
BASIC256
s$ = " \tRosetta Code \v\f\r\n"
print ltrim(s$) # remove leading whitespace
print rtrim(s$) # remove trailing whitespace
print trim(s$) # remove both leading and trailing whitespace
BBC BASIC
REM Remove leading whitespace:
WHILE ASC(A$)<=32 A$ = MID$(A$,2) : ENDWHILE
REM Remove trailing whitespace:
WHILE ASC(RIGHT$(A$))<=32 A$ = LEFT$(A$) : ENDWHILE
REM Remove both leading and trailing whitespace:
WHILE ASC(A$)<=32 A$ = MID$(A$,2) : ENDWHILE
WHILE ASC(RIGHT$(A$))<=32 A$ = LEFT$(A$) : ENDWHILE
BQN
The following program uses an AND-scan (a well known idiom for leading characters) to find the leading whitespace. The whitespace characters are then filtered out from those locations.
Composing the leading and trailing idioms removes whitespace from both sides.
ws ← @+⟨9, 10, 11, 12, 13, 32, 133, 160,
5760, 8192, 8193, 8194, 8195, 8196, 8197, 8198,
8199, 8200, 8201, 8202, 8232, 8233, 8239, 8287,
12288⟩
Lead ← (¬·∧`∊⟜ws)⊸/
Trail ← (¬·∧`⌾⌽∊⟜ws)⊸/
•Show Lead " fs df"
•Show Trail "fdsf asd "
•Show Lead∘Trail " white space "
"fs df"
"fdsf asd"
"white space"
Bracmat
Greedy pattern matching is not Bracmat's strongest field. So instead of a pattern that globs all white space characters, we have a pattern that finds the first non-whitespace character. That character, and the remainder of the subject string, constitute a left trimmed string. To do a right trim, we reverse the string, do a left trim and reverse back.
( ( ltrim
= s
. @( !arg
: ?
( ( %@
: ~( " "
| \a
| \b
| \n
| \r
| \t
| \v
)
)
?
: ?s
)
)
& !s
)
& (rtrim=.rev$(ltrim$(rev$!arg)))
& (trim=.rev$(ltrim$(rev$(ltrim$!arg))))
& (string=" \a Hear
the sound?
\v
\r
")
& out$(str$("Input:[" !string "]"))
& out$(str$("ltrim:[" ltrim$!string "]"))
& out$(str$("rtrim:[" rtrim$!string "]"))
& out$(str$("trim :[" trim$!string "]"))
&
);
Output (Notice the effect of the ancient \a (alarm) and \v (vertical tab)):
Input:[ Hear the sound? ♂ ] ltrim:[Hear the sound? ♂ ] rtrim:[ Hear the sound?] trim :[Hear the sound?]
Burlesque
blsq ) " this is a string "t[
"this is a string "
blsq ) " this is a string "t]
" this is a string"
blsq ) " this is a string "tt
"this is a string"
C
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
char *rtrim(const char *s)
{
while( isspace(*s) || !isprint(*s) ) ++s;
return strdup(s);
}
char *ltrim(const char *s)
{
char *r = strdup(s);
if (r != NULL)
{
char *fr = r + strlen(s) - 1;
while( (isspace(*fr) || !isprint(*fr) || *fr == 0) && fr >= r) --fr;
*++fr = 0;
}
return r;
}
char *trim(const char *s)
{
char *r = rtrim(s);
char *f = ltrim(r);
free(r);
return f;
}
const char *a = " this is a string ";
int main()
{
char *b = rtrim(a);
char *c = ltrim(a);
char *d = trim(a);
printf("'%s'\n'%s'\n'%s'\n", b, c, d);
free(b);
free(c);
free(d);
return 0;
}
Gadget
Gadget C-library: Gadget C-library in Github
#include <gadget/gadget.h>
LIB_GADGET_START
Main
String r,s,t;
Stack{
Store ( r, Trim_r (Upper(" \n\t este mensaje será modificado " )) )
Store ( s, Trim_l (Reverse(Upper(" \n\t este mensaje será odasrever " ))) )
Store ( t, Trim (Upper(" \n\t este mensaje será modificado " )) )
}Stack_off
Print "Right Trim = [%s]\nLeft Trim = [%s]\nAll Trim = [%s]\n",r,s,t;
Free secure r,t, s;
End
- Output:
Right Trim = [ ESTE MENSAJE SERÁ MODIFICADO] Left Trim = [REVERSADO ÁRES EJASNEM ETSE ] All Trim = [ESTE MENSAJE SERÁ MODIFICADO]
C#
using System;
public class TrimExample
{
public static void Main(String[] args)
{
const string toTrim = " Trim me ";
Console.WriteLine(Wrap(toTrim.TrimStart()));
Console.WriteLine(Wrap(toTrim.TrimEnd()));
Console.WriteLine(Wrap(toTrim.Trim()));
}
private static string Wrap(string s)
{
return "'" + s + "'";
}
}
- Output:
'Trim me ' ' Trim me' 'Trim me'
C++
#include <boost/algorithm/string.hpp>
#include <string>
#include <iostream>
int main( ) {
std::string testphrase( " There are unwanted blanks here! " ) ;
std::string lefttrimmed = boost::trim_left_copy( testphrase ) ;
std::string righttrimmed = boost::trim_right_copy( testphrase ) ;
std::cout << "The test phrase is :" << testphrase << "\n" ;
std::cout << "Trimmed on the left side :" << lefttrimmed << "\n" ;
std::cout << "Trimmed on the right side :" << righttrimmed << "\n" ;
boost::trim( testphrase ) ;
std::cout << "Trimmed on both sides :" << testphrase << "\n" ;
return 0 ;
}
- Output:
The test phrase is : There are unwanted blanks here! Trimmed on the left side :There are unwanted blanks here! Trimmed on the right side : There are unwanted blanks here! Trimmed on both sides :There are unwanted blanks here!
Clojure
(use 'clojure.string)
(triml " my string ")
=> "my string "
(trimr " my string ")
=> " my string"
(trim " \t\r\n my string \t\r\n ")
=> "my string"
COBOL
DISPLAY "'" FUNCTION TRIM(str, LEADING) "'"
DISPLAY "'" FUNCTION TRIM(str, TRAILING) "'"
DISPLAY "'" FUNCTION TRIM(str) "'"
DISPLAY "'" FUNCTION TRIML(str) "'"
DISPLAY "'" FUNCTION TRIMR(str) "'"
DISPLAY "'" FUNCTION TRIM(str) "'"
Common Lisp
; Common whitespace characters
(defvar *whitespace* '(#\Space #\Newline #\Tab))
(defvar str " foo bar baz ")
(string-trim *whitespace* str)
; -> "foo bar baz"
(string-left-trim *whitespace* str)
; -> "foo bar baz "
(string-right-trim *whitespace* str)
; -> " foo bar baz"
; Whitespace characters defined by Unicode for
; implementations which support it (e.g. CLISP, SBCL).
; (see http://www.unicode.org/Public/UCD/latest/ucd/PropList.txt)
(defvar *unicode-whitespace*
'(#\u0009 #\u000a #\u000b #\u000c #\u000d
#\u0020 #\u0085 #\u00a0 #\u1680 #\u2000
#\u2001 #\u2002 #\u2003 #\u2004 #\u2005
#\u2006 #\u2007 #\u2008 #\u2009 #\u200a
#\u2028 #\u2029 #\u202f #\u205f #\u3000))
(defvar unicode-str
(format nil "~C~Cfoo~Cbar~Cbaz~C~C"
#\u2000 #\u2003 #\u0020 #\u00a0 #\u0009 #\u202f))
(string-trim *unicode-whitespace* unicode-str)
; -> "foo bar baz"
(string-left-trim *unicode-whitespace* unicode-str)
; -> "foo bar baz "
(string-right-trim *unicode-whitespace* unicode-str)
; -> " foo bar baz"
Crystal
def strip_whitepace(s)
puts s.lstrip()
puts s.rstrip()
puts s.strip()
end
strip_whitepace("\t hello \t")
# => hello
# => hello
# => hello
D
import std.stdio, std.string;
void main() {
auto s = " \t \r \n String with spaces \t \r \n ";
assert(s.stripLeft() == "String with spaces \t \r \n ");
assert(s.stripRight() == " \t \r \n String with spaces");
assert(s.strip() == "String with spaces");
}
Delphi /Pascal
program StripWhitespace;
{$APPTYPE CONSOLE}
uses SysUtils;
const
TEST_STRING = ' String with spaces ';
begin
Writeln('"' + TEST_STRING + '"');
Writeln('"' + TrimLeft(TEST_STRING) + '"');
Writeln('"' + TrimRight(TEST_STRING) + '"');
Writeln('"' + Trim(TEST_STRING) + '"');
end.
DWScript
const TEST_STRING = ' String with spaces ';
PrintLn('"' + TEST_STRING + '"');
PrintLn('"' + TrimLeft(TEST_STRING) + '"');
PrintLn('"' + TrimRight(TEST_STRING) + '"');
PrintLn('"' + Trim(TEST_STRING) + '"');
EasyLang
func iswhite c$ .
if c$ = " " or c$ = "\t" or c$ = "\n"
return 1
.
.
func$ strip s$ top tail .
a = 1
if top = 1
repeat
c$ = substr s$ a 1
until iswhite c$ = 0
a += 1
.
.
b = len s$
if tail = 1
repeat
c$ = substr s$ b 1
until iswhite c$ = 0
b -= 1
.
.
return substr s$ a (b - a + 1)
.
print strip " Hello world " 1 1 & "."
print strip " Hello world " 0 1 & "."
print strip " Hello world " 1 1 & "."
EchoLisp
(define witt
" The limits of my world are the limits of my langage. ")
(string->html (string-trim witt))
→ "The limits of my world are the limits of my langage."
(string->html (string-trim-left witt))
→ "The limits of my world are the limits of my langage. "
(string->html (string-trim-right witt))
→ " The limits of my world are the limits of my langage."
ed
H
,p
,j
t0
t0
1s/^[[:space:]]*(.*)$/Leading whitespace removed: "\1"/
2s/^(.*)(.*[^[:space:]])[[:space:]]*$/Trailing whitespace removed: "\1\2"/
3s/^[[:space:]]*(.*[^[:space:]])[[:space:]]*$/Wrapping whitespace removed: "\1"/
,p
Q
- Output:
$ cat strip-whitespace.ed | ed -lEGs strip-whitespace.input Newline appended Action go! Leading whitespace removed: "Action go! " Trailing whitespace removed: " Action go!" Wrapping whitespace removed: "Action go!"
Elena
ELENA 4.x :
import extensions;
public program()
{
var toTrim := " Trim me ";
console.printLine("'", toTrim.trimLeft(),"'");
console.printLine("'", toTrim.trimRight(),"'");
console.printLine("'", toTrim.trim(),"'");
}
- Output:
'Trim me ' ' Trim me' 'Trim me'
Elixir
str = "\n \t foo \n\t bar \t \n"
IO.inspect String.strip(str)
IO.inspect String.rstrip(str)
IO.inspect String.lstrip(str)
- Output:
"foo \n\t bar" "\n \t foo \n\t bar" "foo \n\t bar \t \n"
Emacs Lisp
As of Emacs 24.4, the subr-x.el library contains string trimming functions:
(string-trim-left " left center right ") ;=> "left center right "
(string-trim-right " left center right ") ;=> " left center right"
(string-trim " left center right ") ;=> "left center right"
This can be emulated by using regex replacement:
(defun string-trim-left (str)
(replace-regexp-in-string "^[ \t\r\n]*" "" str))
(defun string-trim-right (str)
(replace-regexp-in-string "[ \t\r\n]*$" "" str))
(defun string-trim (str)
(string-trim-left (string-trim-right str)))
Erlang
% Implemented by Arjun Sunel
1> string:strip(" Hello World! ", left). %remove leading whitespaces
"Hello World! "
2> string:strip(" Hello World! ", right). % remove trailing whitespaces
" Hello World!"
3> string:strip(" Hello World! ", both). % remove both leading and trailing whitespace
"Hello World!"
Euphoria
A string (sequence) 'A B C' is surrounded by unwanted characters including spaces. The trim() function Trims "all items in the supplied set from both the left end (head/start) and right end (tail/end) of a sequence." It's part of the standard library, std/text.e .
Special characters in a string literal are typed 'escaped' with a '\' followed by one character. Other special characters are written using escaped hexadecimal , example : \x04 to represent hexadecimal ascii 04 or \u2A7C for 4-digit UTF, or more than two digit ascii characters : \u0127.
include std/console.e
include std/text.e
sequence removables = " \t\n\r\x05\u0234\" "
sequence extraSeq = " \x05\r \" A B C \n \t\t \u0234 \r\r \x05 "
extraSeq = trim(extraSeq,removables) --the work is done by the trim function
--only output programming next :
printf(1, "String Trimmed is now: %s \r\n", {extraSeq} ) --print the resulting string to screen
for i = 1 to length(extraSeq) do --loop over each character in the sequence.
printf(1, "String element %d", i) --to look at more detail,
printf(1, " : %d\r\n", extraSeq[i])--print integer values(ascii) of the string.
end for
any_key()
Output:
String Trimmed is now: A B C String element 1 : 65 String element 2 : 32 String element 3 : 32 String element 4 : 66 String element 5 : 32 String element 6 : 32 String element 7 : 67 Press Any Key to continue...
F#
[<EntryPoint>]
let main args =
printfn "%A" (args.[0].TrimStart())
printfn "%A" (args.[0].TrimEnd())
printfn "%A" (args.[0].Trim())
0
>rosetta " a string " "a string " " a string" "a string"
Factor
USE: unicode
" test string " [ blank? ] trim ! leading and trailing
" test string " [ blank? ] trim-head ! only leading
" test string " [ blank? ] trim-tail ! only trailing
Forth
Modern Forth advocates the use of "stack strings". These are simply the memory address of the text on the stack followed by the length of the string on the stack. The advantage of using stack strings is that string manipulation is done without resorting to copying the strings to temporary memory. This makes string manipulation very fast. The values left on the stack are suitable as input arguments for further processing so function concatenation is possible to create more complex functions.
After the string processing is completed on the stack the program can print or copy back to memory as required.
: -leading ( addr len -- addr' len' ) \ called "minus-leading"
begin
over c@ bl = \ fetch character at addr, test if blank (space)
while
\ cut 1 leading character by incrementing address & decrementing length
1 /string \ "cut-string"
repeat ;
The counterpart function "-trailing" is normally part of a standard forth system, so by concatenating both we create a "STRIP" function.
: strip ( addr len -- addr' len') -leading -trailing ;
Test at the Forth console
: mystring s" Trim this string. " ; mstring type Trim this string. ok mstring -leading type Trim this string. ok mystring -trailing type Trim this string. ok mytring strip type Trim this string. ok
Fortran
The problem is that Fortran does not offer a "string" type, which is to say a store of characters plus a current length. Leaving aside later Fortrans where one can create a data type and associated operations, one must deal with CHARACTER style items, though they were not available in early Fortran. Thus, CHARACTER*(60) TEXT
creates a variable capable of storing sixty characters and there is no "varying" attribute as in pl/i to signify a current length as well. The intrinsic function LEN(TEXT) returns 60, so it is really the "size" function. Functions can return CHARACTER types, but, only of a specified size, fixed at compile time. It is common then to have many trailing spaces in such variables. An expression TEXT(start:stop)
means select characters start to stop of TEXT.
A function LEN_TRIM(x) may be supplied, returning the index of the last non-blank character. And only of spaces: tabs and suchlike are not blanks. Thus, to remove trailing spaces, TEXT(1:LEN_TRIM(TEXT))
would do the trick. There may also be available an intrinsic function TRIM, which removes leading and trailing spaces, thus TRIM(TEXT)
and which does so for any length of TEXT and any length of result, unlike user-written functions that have a fixed result length.
Otherwise, one must write integer functions such as ISTNB(x) and LSTNB(x) to return the first and last non-blank character of x and use them in something like TEXT(ISTNB(TEXT):LSTNB(TEXT))
wherever one wants the trimmed content of TEXT. Correspondingly TEXT(ISTNB(TEXT):LEN(TEXT))
to omit leading spaces and TEXT(1:LSTNB(TEXT))
to omit trailing spaces. Such user-written functions can make their own choices about tabs and any other special characters.
FreeBASIC
' FB 1.05.0 Win64
Const whitespace = !" \t\n\v\f\r"
Dim s As String = !" \tRosetta Code \v\f\r\n"
Dim s1 As String = LTrim (s, Any whitespace)
Dim s2 As String = RTrim (s, Any whitespace)
Dim s3 As String = Trim (s, Any whitespace)
' Under Windows console :
' "vertical tab" displays as ♂
' "form feed" displays as ♀
' the other whitespace characters do what it says on the tin
Print "Untrimmed" , "=> "; s
Print "Left Trimmed" , "=> "; s1
Print "Right Trimmed" , "=> "; s2
Print "Fully Trimmed" , "=> "; s3
Print
Print "Untrimmed" , "=> Length = "; Len(s)
Print "Left trimmed" , "=> Length = "; Len(s1)
Print "Right trimmed" , "=> Length = "; Len(s2)
Print "Fully trimmed" , "=> Length = "; Len(s3)
Sleep
- Output:
Untrimmed => Rosetta Code ♂♀ Left Trimmed => Rosetta Code ♂♀ Right Trimmed => Rosetta Code Fully Trimmed => Rosetta Code Untrimmed => Length = 20 Left trimmed => Length = 17 Right trimmed => Length = 15 Fully trimmed => Length = 12
FutureBasic
window 1
CFCharacterSetRef set, invSet
CFStringRef s, s1, s2, s3
NSUInteger index
CFRange range
set = fn CharacterSetWhitespaceAndNewlineSet
invSet = fn CharacterSetInvertedSet( set )
text ,,,,, 200
s = @" a string "// 5 leading spaces, 8 trailing spaces
print s, len(s)@" chars"
// left trim
index = 0
range = fn StringRangeOfCharacterFromSet( s, invSet )
if ( range.location != NSNotFound ) then index = range.location
s1 = fn StringSubstringFromIndex( s, index )
print s1, len(s1)@" chars"
// right trim
index = len(s)
range = fn StringRangeOfCharacterFromSetWithOptions( s, invSet, NSBackwardsSearch )
if ( range.location != NSNotFound ) then index = range.location + 1
s2 = fn StringSubstringToIndex( s, index )
print s2, len(s2)@" chars"
// trim
s3 = fn StringByTrimmingCharactersInSet( s, set )
print s3, len(s3)@" chars"
HandleEvents
- Output:
a string 21 chars a string 16 chars a string 13 chars a string 8 chars
Gambas
Click this link to run this code
Public Sub Main()
Dim sString As String = " Hello world! "
Print sString & "\tString length = " & Len(sString) & " - Original string"
Print LTrim(sString) & "\tString length = " & Len(LTrim(sString)) & " - String with leading whitespace removed"
Print RTrim(sString) & "\tString length = " & Len(RTrim(sString)) & " - String with trailing whitespace removed"
Print Trim(sString) & "\t\tString length = " & Len(Trim(sString)) & " - String with both leading and trailing whitespace removed"
End
Output:
Hello world! String length = 20 - Original string Hello world! String length = 16 - String with leading whitespace removed Hello world! String length = 16 - String with trailing whitespace removed Hello world! String length = 12 - String with both leading and trailing whitespace removed
Go
package main
import (
"fmt"
"strings"
"unicode"
)
var simple = `
simple `
func main() {
show("original", simple)
show("leading ws removed", strings.TrimLeftFunc(simple, unicode.IsSpace))
show("trailing ws removed", strings.TrimRightFunc(simple, unicode.IsSpace))
// equivalent to strings.TrimFunc(simple, unicode.IsSpace)
show("both removed", strings.TrimSpace(simple))
}
func show(label, str string) {
fmt.Printf("%s: |%s| %v\n", label, str, []rune(str))
}
Example text is shows a leading linefeed and tab, and three trailing spaces. The code uses the Unicode definition of whitespace. Other defintions could be implemented with a custom function given to TrimXFunc.
Output below shows the text surrounded by vertical bars to show the extent of whitespace, followed by a list of the character values in the string, to show exactly what whitespace is present.
original: | simple | [10 9 115 105 109 112 108 101 32 32 32] leading ws removed: |simple | [115 105 109 112 108 101 32 32 32] trailing ws removed: | simple| [10 9 115 105 109 112 108 101] both removed: |simple| [115 105 109 112 108 101]
Groovy
Solution uses StringUtils class from Apache Commons "Lang" library:
//Grape setup to get library
@Grab('org.apache.commons:commons-lang3:3.0.1')
import static org.apache.commons.lang3.StringUtils.*
def abc = '\r\n\t abc \r\n\t'
def printTest = {
println ('|' + it + '|')
}
println 'Unstripped\n------------'
printTest abc
println '============\n\nStripped\n------------'
printTest strip(abc)
println '============\n\nLeft Stripped\n------------'
printTest stripStart(abc, null)
println '============\n\nRight Stripped\n------------'
printTest stripEnd(abc, null)
println '============'
- Output:
Unstripped ------------ | abc | ============ Stripped ------------ |abc| ============ Left Stripped ------------ |abc | ============ Right Stripped ------------ | abc| ============
Haskell
import Data.Char (isSpace)
import Data.List (dropWhileEnd)
trimLeft :: String -> String
trimLeft = dropWhile isSpace
trimRight :: String -> String
trimRight = dropWhileEnd isSpace
trim :: String -> String
trim = trimLeft . trimRight
Icon and Unicon
This solution takes the phrase "other such characters that have no corresponding graphical representation" quite literallly.
procedure main()
unp := &cset[1+:32]++' \t'++&cset[127:0] # all 'unprintable' chars
s := " Hello, people of earth! "
write("Original: '",s,"'")
write("leading trim: '",reverse(trim(reverse(s),unp)),"'")
write("trailing trim: '",trim(s,unp),"'")
write("full trim: '",reverse(trim(reverse(trim(s,unp)),unp)),"'")
end
- Sample run:
->trim Original: ' Hello, people of earth! ' leading trim: 'Hello, people of earth! ' trailing trim: ' Hello, people of earth!' full trim: 'Hello, people of earth!' ->
J
Note: The quote
verb is only used to enclose the resulting string in single quotes so the beginning and end of the new string are visible.
require 'strings' NB. the strings library is automatically loaded in versions from J7 on
quote dlb ' String with spaces ' NB. delete leading blanks
'String with spaces '
quote dtb ' String with spaces ' NB. delete trailing blanks
' String with spaces'
quote dltb ' String with spaces ' NB. delete leading and trailing blanks
'String with spaces'
In addition deb
(delete extraneous blanks) will trim both leading and trailing blanks as well as replace consecutive spaces within the string with a single space.
quote deb ' String with spaces ' NB. delete extraneous blanks
'String with spaces'
These existing definitions can be easily amended to include whitespace other than spaces if desired.
whpsc=: ' ',TAB NB. define whitespace as desired
dlws=: }.~ (e.&whpsc i. 0:) NB. delete leading whitespace (spaces and tabs)
dtws=: #~ ([: +./\. -.@:e.&whpsc) NB. delete trailing whitespace
dltws=: #~ ([: (+./\ *. +./\.) -.@:e.&whpsc) NB. delete leading & trailing whitespace
dews=: #~ (+. (1: |. (> </\)))@(-.@:e.&whpsc) NB. delete extraneous whitespace
Java
Java has the trim and strip operations. Both will achieve a similar result.
The trim
method works on Unicode values under 0x20. Whereas, strip will remove all Unicode white-space characters.
" abc".stripLeading()
"abc ".stripTrailing()
" abc ".strip()
" abc ".trim()
For more control over what characters should be removed, you could implement your own methods.
String removeLeading(String string, char[] characters) {
int index = 0;
for (char characterA : string.toCharArray()) {
for (char characterB : characters) {
if (characterA != characterB)
return string.substring(index);
}
index++;
}
return string;
}
String removeTrailing(String string, char[] characters) {
for (int index = string.length() - 1; index >= 0; index--) {
for (char character : characters) {
if (string.charAt(index) != character)
return string.substring(0, index + 1);
}
}
return string;
}
An alternate demonstration
Java offers String.trim
. However, this function only strips out ASCII control characters. As such it should generally be avoided for processing text.
Rather, the function Character.isWhitespace
should be used to strip out any Unicode whitespaces. Note that the Java implementation slightly deviates from the strict Unicode definition: For example, non-breaking spaces are not considered whitespace by Java. This is fine for stripping leading/trailing whitespaces, as a non-breaking space generally should not appear there, but is something to keep in mind.
Left trim and right trim taken from here.
public class Trims{
public static String ltrim(String s) {
int i = 0;
while (i < s.length() && Character.isWhitespace(s.charAt(i))) {
i++;
}
return s.substring(i);
}
public static String rtrim(String s) {
int i = s.length() - 1;
while (i > 0 && Character.isWhitespace(s.charAt(i))) {
i--;
}
return s.substring(0, i + 1);
}
public static String trim(String s) {
return rtrim(ltrim(s));
}
public static void main(String[] args) {
String s = " \t \r \n String with spaces \u2009 \t \r \n ";
System.out.printf("[%s]\n", ltrim(s));
System.out.printf("[%s]\n", rtrim(s));
System.out.printf("[%s]\n", trim(s));
}
}
Supplementary-correct version
Unicode *happens* to not have any whitespace characters outside of Basic Multilingual Plane (aka, they all fit inside a char
). However, this not something you should generally rely on, and should assume your strings contain characters in the Supplementary Planes. As such, instead of iterating using String.charAt
, prefer instead using String.codePointAt
and String.codePointBefore
, iterating over actual Unicode Code Points:
public static String ltrim(String s) {
int offset = 0;
while (offset < s.length()) {
int codePoint = s.codePointAt(offset);
if (!Character.isWhitespace(codePoint)) break;
offset += Character.charCount(codePoint);
}
return s.substring(offset);
}
public static String rtrim(String s) {
int offset = s.length();
while (offset > 0) {
int codePoint = s.codePointBefore(offset);
if (!Character.isWhitespace(codePoint)) break;
offset -= Character.charCount(codePoint);
}
return s.substring(0, offset);
}
JavaScript
{
let s = " \t String with spaces \t ";
// a future version of ECMAScript will have trimStart(). Some current
// implementations have trimLeft().
console.log("original: '" + s + "'");
console.log("trimmed left: '" + s.replace(/^\s+/,'') + "'");
// a future version of ECMAScript will have trimEnd(). Some current
// implementations have trimRight().
console.log("trimmed right: '" + s.replace(/\s+$/,'') + "'");
console.log("trimmed both: '" + s.trim() + "'");
}
- Output:
original: ' String with spaces ' trimmed left: 'String with spaces ' trimmed right: ' String with spaces' trimmed both: 'String with spaces'
Or, composing from generic primitives:
(() => {
'use strict';
// stripStart :: Text -> Text
let stripStart = s => dropWhile(isSpace, s);
// stripEnd :: Text -> Text
let stripEnd = s => dropWhileEnd(isSpace, s);
// strip :: Text -> Text
let strip = s => dropAround(isSpace, s);
// OR: let strip = s => s.trim();
// GENERIC FUNCTIONS
// dropAround :: (Char -> Bool) -> Text -> Text
let dropAround = (p, s) => dropWhile(p, dropWhileEnd(p, s));
// dropWhile :: (a -> Bool) -> [a] -> [a]
let dropWhile = (p, xs) => {
for (var i = 0, lng = xs.length;
(i < lng) && p(xs[i]); i++) {}
return xs.slice(i);
}
// dropWhileEnd :: (Char -> Bool) -> Text -> Text
let dropWhileEnd = (p, s) => {
for (var i = s.length; i-- && p(s[i]);) {}
return s.slice(0, i + 1);
}
// isSpace :: Char -> Bool
let isSpace = c => /\s/.test(c);
// show :: a -> String
let show = x => JSON.stringify(x, null, 2);
// TEST
let strText = " \t\t \n \r Much Ado About Nothing \t \n \r ";
return show([stripStart, stripEnd, strip]
.map(f => '-->' + f(strText) + '<--'));
})();
- Output:
[ "-->Much Ado About Nothing \t \n \r <--", "--> \t\t \n \r Much Ado About Nothing<--", "-->Much Ado About Nothing<--" ]
jq
Recent versions of jq (since July 2014) support PCRE regex operations; \p{_} character classes are also supported. The following accordingly uses \p{Cc} as that corresponds to ASCII 0x00–0x1F.
Notice that since jq strings are JSON strings, one must, for example, write "\\s" for the regex '\s'.
def lstrip: sub( "^[\\s\\p{Cc}]+"; "" );
def rstrip: sub( "[\\s\\p{Cc}]+$"; "" );
def strip: lstrip | rstrip;
Examples:
def demo:
"lstrip: \(lstrip)",
"rstrip: \(rstrip)",
"strip: \(strip)" ;
(" \t \r \n String with spaces \t \r \n ",
"� <- control A",
"\u0001 \u0002 <- ^A ^B"
) | demo
- Output:
$ jq -n -f Strip_whitespace_top_tail.jq
"lstrip: String with spaces \t \r \n "
"rstrip: \t \r \n String with spaces"
"strip: String with spaces"
"rstrip: \u0001 <- control A"
"strip: <- control A"
"lstrip: <- ^A ^B"
"rstrip: \u0001 \u0002 <- ^A ^B"
"strip: <- ^A ^B"
Jsish
Using echo-mode unitTest lines. Lines starting with semicolon are echoed and captured during test.
#!/usr/bin/env jsish
/* Strip whitespace from string, in Jsi */
var str = ' \n \t String with whitespace \t \n ';
;'Original';
;str;
;'Default trim characters are space, tab, newline, carriage return';
;'trimLeft, remove leading characters';
;str.trimLeft();
;'trimRight, remove trailing characters';
;str.trimRight();
;'trim, removes leading and trailing';
;str.trim();
/*
=!EXPECTSTART!=
'Original'
str ==>
String with whitespace
'Default trim characters are space, tab, newline, carriage return'
'trimLeft, remove leading characters'
str.trimLeft() ==> String with whitespace
'trimRight, remove trailing characters'
str.trimRight() ==>
String with whitespace
'trim, removes leading and trailing'
str.trim() ==> String with whitespace
=!EXPECTEND!=
*/
- Output:
prompt$ jsish -u stripWhitespace.jsi [PASS] stripWhitespace.jsi prompt$ jsish --U stripWhitespace.jsi 'Original' str ==> String with whitespace 'Default trim characters are space, tab, newline, carriage return' 'trimLeft, remove leading characters' str.trimLeft() ==> String with whitespace 'trimRight, remove trailing characters' str.trimRight() ==> String with whitespace 'trim, removes leading and trailing' str.trim() ==> String with whitespace
Julia
julia> s = " \t \r \n String with spaces \t \r \n "
" \t \r \n String with spaces \t \r \n "
julia> lstrip(s)
"String with spaces \t \r \n "
julia> rstrip(s)
" \t \r \n String with spaces"
julia> strip(s)
"String with spaces"
K
dlb: {((" "<x)?1)_x}
dtb: {(-(|" "<x)?1)_x}
dlb " this is a test "
"this is a test "
dtb " this is a test "
" this is a test"
dtb dlb " this is a test "
"this is a test"
dtb dlb "this is a test"
"this is a test"
tested with ngn/k
Kotlin
It is worth pointing out that Kotlin, unlike Java, has String.trimStart
and String.trimEnd
. More importantly though, Kotlin’s String.trim
actually trims whitespace as defined by Unicode, whereas Java’s just strips Unicode control characters.
Kotlin’s trim
family of functions also optionally accept a predicate, which can further customize the stripping behavior, if Unicode whitespace is not what is desired.
fun main(args: Array<String>) {
val s = " \tRosetta Code \r \u2009 \n"
println("Untrimmed => [$s]")
println("Left Trimmed => [${s.trimStart()}]")
println("Right Trimmed => [${s.trimEnd()}]")
println("Fully Trimmed => [${s.trim()}]")
}
- Output:
Untrimmed => [ Rosetta Code ] Left Trimmed => [Rosetta Code ] Right Trimmed => [ Rosetta Code] Fully Trimmed => [Rosetta Code]
Ksh
#!/bin/ksh
# Strip whitespace from a string/Top and tail
# # Variables:
#
str=${1:-" This is a test. "}
# # Functions:
#
# # Function _striphead(str) - Return str with leading while space stripped
#
function _striphead {
typeset _str ; _str="$1"
echo "${_str##*(\s)}"
}
# # Function _striptail(str) - Return str with trailing while space stripped
#
function _striptail {
typeset _str ; _str="$1"
while [[ ${_str} != ${_str%+(\s)} ]]; do
_str=${_str%+(\s)}
done
echo "${_str}"
}
######
# main #
######
printf ">%s< (Unstripped %d chars)\n" "${str}" ${#str}
sstr=$(_striphead "${str}")
printf ">%s< (Strip leading (%d chars))\n" "${sstr}" $(( ${#str}-${#sstr} ))
sstr=$(_striptail "${str}")
printf ">%s< (Strip trailing (%d chars))\n" "${sstr}" $(( ${#str}-${#sstr} ))
sstr=$(_striphead "$(_striptail "${str}")")
printf ">%s< (Strip both (%d chars))\n" "${sstr}" $(( ${#str}-${#sstr} ))
- Output:
> This is a test. < (Unstripped 19 chars)>This is a test. < (Strip leading (1 chars)) > This is a test.< (Strip trailing (3 chars))
>This is a test.< (Strip both (4 chars))
Lambdatalk
initial string : {def string ___String with "_" displaying space_____}
-> string ___String with "_" displaying space_____
trimLeft : {S.replace ^_+ by in {string}}
-> String with "_" displaying space_____
trimRight : {S.replace _+$ by in {string}}
-> ___String with "_" displaying space
trimBoth : {S.replace _+$ by in {S.replace ^_+ by in {string}}}
-> String with "_" displaying space
Lasso
Note that the example below uses the retarget operator ("&") to output as the trim method modifies the string in place.
The '>' and '<' strings have been included in this example to demonstrate the whitespace trim.
// String with leading whitespace removed
'>' + (' \t Hello')->trim& + '<'
// String with trailing whitespace removed
'>' + ('Hello \t ')->trim& + '<'
// String with both leading and trailing whitespace removed
'>' + (' \t Hello \t ')->trim& + '<'
Liberty BASIC
a$=" This is a test "
'LB TRIM$ removes characters with codes 0..31 as well as a space(code 32)
'So these versions of ltrim rtrim remove them too
'a$=" "+chr$(31)+"This is a test"+chr$(31)+" "
print "Source line"
print ">";a$;"<"
print "Strip left"
print ">";ltrim$(a$);"<"
print "Strip right"
print ">";rtrim$(a$);"<"
print "Strip both"
print ">";trim$(a$);"<"
end
function ltrim$(a$)
c$=trim$(a$+".")
ltrim$ = mid$(c$, 1, len(c$)-1)
end function
function rtrim$(a$)
c$=trim$("."+a$)
rtrim$ = mid$(c$, 2)
end function
Logtalk
Using atoms for representing strings and assuming an ASCII text encoding:
:- object(whitespace).
:- public(trim/4).
trim(String, TrimLeft, TrimRight, TrimBoth) :-
trim_left(String, TrimLeft),
trim_right(String, TrimRight),
trim_right(TrimLeft, TrimBoth).
trim_left(String, TrimLeft) :-
atom_codes(String, Codes),
trim(Codes, TrimCodes),
atom_codes(TrimLeft, TrimCodes).
trim_right(String, TrimRight) :-
atom_codes(String, Codes),
list::reverse(Codes, ReverseCodes),
trim(ReverseCodes, ReverseTrimCodes),
list::reverse(ReverseTrimCodes, TrimCodes),
atom_codes(TrimRight, TrimCodes).
trim([], []).
trim([InCode| InCodes], OutCodes) :-
( InCode =< 32 ->
trim(InCodes, OutCodes)
; OutCodes = [InCode| InCodes]
).
:- end_object.
Sample output:
| ?- whitespace::trim('\n\t Rosetta Code \t\n', TrimLeft, TrimRight, TrimBoth).
TrimLeft = 'Rosetta Code \t\n',
TrimRight = '\n\t Rosetta Code',
TrimBoth = 'Rosetta Code'
yes
Lua
str = " \t \r \n String with spaces \t \r \n "
print( string.format( "Leading whitespace removed: %s", str:match( "^%s*(.+)" ) ) )
print( string.format( "Trailing whitespace removed: %s", str:match( "(.-)%s*$" ) ) )
print( string.format( "Leading and trailing whitespace removed: %s", str:match( "^%s*(.-)%s*$" ) ) )
M2000 Interpreter
Module CheckIt {
filter$=chr$(0)
for i=1 to 31:filter$+=chr$(i):next
a$=chr$(9)+" There are unwanted blanks here! "+chr$(9)
a$=filter$(a$,filter$) ' exclude non printable characters
\\ string encoded as UTF16LE
Print Len(a$)=39
Print(ltrim$(a$))
Print(rtrim$(a$))
Print(trim$(a$))
\\ string encoded as ANSI base to Locale
oldlocale=Locale
Locale 1033
a$=str$(a$)
Print Len(a$)=19.5 ' unit for length is a word (2 bytes), so 19.5 means 19.5*2 bytes= 39 bytes
PrintAnsi(ltrim$(a$ as byte))
PrintAnsi(rtrim$(a$ as byte))
PrintAnsi(trim$(a$ as byte))
Locale oldlocale
Sub Print(a$)
Print "*"+a$+"*"
End Sub
Sub PrintAnsi(a$)
Print "*"+chr$(a$)+"*"
End Sub
}
Checkit
- Output:
True *There are unwanted blanks here! * * There are unwanted blanks here!* *There are unwanted blanks here!* True *There are unwanted blanks here! * * There are unwanted blanks here!* *There are unwanted blanks here!*
Maple
str := " \t \r \n String with spaces \t \r \n ";
with(StringTools):
TrimLeft(str);
TrimRight(str);
Trim(str);
Mathematica /Wolfram Language
StringTrim[" \n\t string with spaces \n \t "]
MATLAB / Octave
% remove trailing whitespaces
str = str(1:find(~isspace(str),1,'last'));
% remove leading whitespaces
str = str(find(~isspace(str),1):end);
% removes leading and trailing whitespaces, vectorized version
f = ~isspace(str);
str = str(find(f,1,'first'):find(f,1,'last');
% a built-in function, removes leading and trailing whitespaces
str = strtrim(str);
Mercury
:- module top_and_tail.
:- interface.
:- import_module io.
:- pred main(io::di, io::uo) is det.
:- implementation.
:- import_module list, string.
main(!IO) :-
TestPhrase = "\t\r\n String with spaces \t\r\n ",
io.format("leading ws removed: %s\n", [s(lstrip(TestPhrase))], !IO),
io.format("trailing ws removed: %s\n", [s(rstrip(TestPhrase))], !IO),
io.format("both removed: %s\b", [s(strip(TestPhrase))], !IO).
Nemerle
def str = "\t\n\t A string with\nwhitespace\n\n\t ";
WriteLine(str.TrimStart());
WriteLine(str.TrimEnd());
WriteLine(str.Trim()); // both ends at once, of course, internal whitespace is preserved in all 3
NetRexx
NetRexx provides a strip() method which can be used to remove all of a single character from the head and/or tail of a string. To remove all whitespace characters from a string requires a little more work:
/* NetRexx */
options replace format comments java crossref symbols nobinary
runSample(arg)
return
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
method stripWhitespace(sstring, soption = 'BOTH') public static
wsChars = getWhitspaceCharacterString()
po1 = sstring.verify(wsChars)
if po1 = 0 then do
sstring = ''
end
else do
po2 = sstring.length - (sstring.reverse().verify(wsChars) - 1) + 1
ss = sstring
parse ss sl =(po1) sm =(po2) st
if po1 <= 1 then sl = ''
soption = soption.upper()
select
when 'BOTH'.abbrev(soption, 1) then sstring = sm
when 'LEADING'.abbrev(soption, 1) then sstring = sm || st
when 'TRAILING'.abbrev(soption, 1) then sstring = sl || sm
otherwise sstring = sm
end
end
return sstring
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* Create an array containing a useful subset of unicode whitespace characters
*
* @return an array of unicode whitespace characters
* @see http://www.fileformat.info/info/unicode/category/index.htm
*/
method getWhitspaceCharacters() public static returns Rexx[]
wsChars = [ -
/* LINE SEPARATOR [Zi] */ '\u2028', /* PARAGRAPH SEPARATOR [Zp] */ '\u2029', -
/* SPACE [Zs] */ '\u0020', /* NO-BREAK SPACE [Zs] */ '\u00A0', -
/* OGHAM SPACE MARK [Zs] */ '\u1680', /* MONGOLIAN VOWEL SEPARATOR [Zs] */ '\u180E', -
/* EN QUAD [Zs] */ '\u2000', /* EM QUAD [Zs] */ '\u2001', -
/* EN SPACE [Zs] */ '\u2002', /* EM SPACE [Zs] */ '\u2003', -
/* THREE-PER-EM SPACE [Zs] */ '\u2004', /* FOUR-PER-EM SPACE [Zs] */ '\u2005', -
/* SIX-PER-EM SPACE [Zs] */ '\u2006', /* FIGURE SPACE [Zs] */ '\u2007', -
/* PUNCTUATION SPACE [Zs] */ '\u2008', /* THIN SPACE [Zs] */ '\u2009', -
/* HAIR SPACE [Zs] */ '\u200A', /* NARROW NO-BREAK SPACE [Zs] */ '\u202F', -
/* MEDIUM MATHEMATICAL SPACE [Zs] */ '\u3000', /* IDIOGRAPHIC SPACE [Zs] */ '\u205F', -
/* BACKSPACE [Cc] */ '\u0008', /* CHARACTER TABULATION, HT [Cc] */ '\u0009', -
/* LINE FEED (LF) [Cc] */ '\u000A', /* LINE TABULATION (VT) [Cc] */ '\u000B', -
/* FORM FEED (FF) [Cc] */ '\u000C', /* CARRIAGE RETURN (CR) [Cc] */ '\u000D', -
/* INFORMATION SEPARATOR FOUR [Cc] */ '\u001C', /* INFORMATION SEPARATOR THREE [Cc] */ '\u001D', -
/* INFORMATION SEPARATOR TWO [Cc] */ '\u001E', /* INFORMATION SEPARATOR ONE [Cc] */ '\u001F', -
/* NEXT LINE (NEL) [Cc] */ '\u0085', -
/* ZERO WIDTH SPACE [Cf] */ '\u200B', /* ZERO WIDTH NO-BREAK SPACE [Cf] */ '\uFEFF' -
]
return wsChars
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
method getWhitspaceCharacterString() public static returns Rexx
wsCharstring = ''
loop wsChar over getWhitspaceCharacters()
wsCharstring = wsCharstring || wsChar
end wsChar
return wsCharstring
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
method runSample(arg) public static
sstrings = [ -
' \u0020 \u0009 \u000D\r \n \u2029\uFEFF1 String with white space. \t \r \n \u1680 ', -
' \t 2 String with white space. \t ', -
'3 String with white space. \t', -
' \t 4 String with white space.', -
'5 String with white space.', -
'\u0020\u0009\u2029\uFEFF\u1680\u2006', -
' ', -
'' -
]
loop sstringO over sstrings
sstringL = stripWhitespace(sstringO, 'l')
sstringT = stripWhitespace(sstringO, 't')
sstringB = stripWhitespace(sstringO)
say ' Original string ['sstringO']'
say ' strip leading ['sstringL']'
say ' strip trailing ['sstringT']'
say ' strip both ['sstringB']'
say
end sstringO
return
Output:
Original string [ 1 String with white space. ] strip leading [1 String with white space. ] strip trailing [ 1 String with white space.] strip both [1 String with white space.] Original string [ 2 String with white space. ] strip leading [2 String with white space. ] strip trailing [ 2 String with white space.] strip both [2 String with white space.] Original string [3 String with white space. ] strip leading [3 String with white space. ] strip trailing [3 String with white space.] strip both [3 String with white space.] Original string [ 4 String with white space.] strip leading [4 String with white space.] strip trailing [ 4 String with white space.] strip both [4 String with white space.] Original string [5 String with white space.] strip leading [5 String with white space.] strip trailing [5 String with white space.] strip both [5 String with white space.] Original string [ ] strip leading [] strip trailing [] strip both [] Original string [ ] strip leading [] strip trailing [] strip both [] Original string [] strip leading [] strip trailing [] strip both []
NewLISP
(setq str " this is a string ")
;; trim leading blanks
(trim str " " "")
;; trim trailing blanks
(trim str "" " ")
;; trim both leading and trailing blanks
(trim str)
Nim
import strutils
let s = "\t \v \r String with spaces \n \t \f"
echo "“", s, "”"
echo("*** Stripped of leading spaces ***")
echo "“", s.strip(trailing = false), "”"
echo("*** Stripped of trailing spaces ***")
echo "“", s.strip(leading = false), "”"
echo("*** Stripped of leading and trailing spaces ***")
echo "“", s.strip(), "”"
- Output:
“ String with spaces ” *** Stripped of leading spaces *** “String with spaces ” *** Stripped of trailing spaces *** “ String with spaces” *** Stripped of leading and trailing spaces *** “String with spaces”
Nu
# leading (left):
$text | str trim -l
# trailing (right):
$text | str trim -r
# both:
$text | str trim
Oberon-2
Oxford Oberon-2
MODULE Trim;
IMPORT Out,Strings,SYSTEM;
CONST
(* whitespaces *)
HT = 09X; VT = 0BX; FF = 0CX; GS = 1DX; US = 1FX;
LF = 0AX; CR = 0DX; FS = 1CX; RS = 1EX; SPC = 20X;
PROCEDURE LTrim(VAR s: ARRAY OF CHAR);
VAR
j : INTEGER;
BEGIN
j := 0;
WHILE (s[j] = HT) OR (s[j] = LF) OR (s[j] = VT) OR (s[j] = CR) OR
(s[j] = FF) OR (s[j] = FS) OR (s[j] = FS) OR (s[j] = GS) OR
(s[j] = RS) OR (s[j] = US) OR (s[j] = SPC) DO INC(j) END;
SYSTEM.MOVE(SYSTEM.ADR(s[j]),SYSTEM.ADR(s[0]),LEN(s) - j);
END LTrim;
PROCEDURE RTrim(VAR s: ARRAY OF CHAR);
VAR
j : INTEGER;
BEGIN
j := LEN(s) - 1;
WHILE (j >= 0) & (s[j] = 0X) DO DEC(j) END;
WHILE (j >= 0) & ((s[j] = HT) OR (s[j] = LF) OR (s[j] = VT) OR (s[j] = CR) OR
(s[j] = FF) OR (s[j] = FS) OR (s[j] = FS) OR (s[j] = GS) OR
(s[j] = RS) OR (s[j] = US) OR (s[j] = SPC)) DO
s[j] := 0X;
DEC(j)
END
END RTrim;
PROCEDURE Trim(VAR s: ARRAY OF CHAR);
BEGIN
LTrim(s);
RTrim(s)
END Trim;
VAR
s: ARRAY 100 OF CHAR;
BEGIN
s := " A AAA";
Out.Char("[");Out.String(s);Out.String("]=");Out.Char(HT);LTrim(s);Out.Char("[");Out.String(s);Out.Char("]");Out.Ln;
s := "AAA A ";
Out.Char("[");Out.String(s);Out.String("]=");Out.Char(HT);RTrim(s);Out.Char("[");Out.String(s);Out.Char("]");Out.Ln;
s := " A AA A ";
Out.Char("[");Out.String(s);Out.String("]=");Out.Char(HT);Trim(s);Out.Char("[");Out.String(s);Out.Char("]");Out.Ln;
s := " ";
Out.Char("[");Out.String(s);Out.String("]=");Out.Char(HT);Trim(s);Out.Char("[");Out.String(s);Out.Char("]");Out.Ln;
s := " ";
Out.Char("[");Out.String(s);Out.String("]=");Out.Char(HT);RTrim(s);Out.Char("[");Out.String(s);Out.Char("]");Out.Ln;
s := " ";
Out.Char("[");Out.String(s);Out.String("]=");Out.Char(HT);LTrim(s);Out.Char("[");Out.String(s);Out.Char("]");Out.Ln;
Out.Char("[");Out.String(s);Out.String("]=");Out.Char(HT);RTrim(s);Out.Char("[");Out.String(s);Out.Char("]");Out.Ln;
Out.Char("[");Out.String(s);Out.String("]=");Out.Char(HT);LTrim(s);Out.Char("[");Out.String(s);Out.Char("]");Out.Ln;
END Trim.
- Output:
[ A AAA]= [A AAA] [AAA A ]= [AAA A] [ A AA A ]= [A AA A] [ ]= [] [ ]= [] [ ]= [] []= [] []= []
Objective-C
#import <Foundation/Foundation.h>
@interface NSString (RCExt)
-(NSString *) ltrim;
-(NSString *) rtrim;
-(NSString *) trim;
@end
@implementation NSString (RCExt)
-(NSString *) ltrim
{
NSInteger i;
NSCharacterSet *cs = [NSCharacterSet whitespaceAndNewlineCharacterSet];
for(i = 0; i < [self length]; i++)
{
if ( ![cs characterIsMember: [self characterAtIndex: i]] ) break;
}
return [self substringFromIndex: i];
}
-(NSString *) rtrim
{
NSInteger i;
NSCharacterSet *cs = [NSCharacterSet whitespaceAndNewlineCharacterSet];
for(i = [self length] -1; i >= 0; i--)
{
if ( ![cs characterIsMember: [self characterAtIndex: i]] ) break;
}
return [self substringToIndex: (i+1)];
}
-(NSString *) trim
{
return [self
stringByTrimmingCharactersInSet:
[NSCharacterSet whitespaceAndNewlineCharacterSet]];
}
@end
int main()
{
@autoreleasepool {
NSString *s = @" this is a string ";
NSLog(@"'%@'", s);
NSLog(@"'%@'", [s ltrim]);
NSLog(@"'%@'", [s rtrim]);
NSLog(@"'%@'", [s trim]);
}
return 0;
}
OCaml
let left_pos s len =
let rec aux i =
if i >= len then None
else match s.[i] with
| ' ' | '\n' | '\t' | '\r' -> aux (succ i)
| _ -> Some i
in
aux 0
let right_pos s len =
let rec aux i =
if i < 0 then None
else match s.[i] with
| ' ' | '\n' | '\t' | '\r' -> aux (pred i)
| _ -> Some i
in
aux (pred len)
let trim s =
let len = String.length s in
match left_pos s len, right_pos s len with
| Some i, Some j -> String.sub s i (j - i + 1)
| None, None -> ""
| _ -> assert false
let ltrim s =
let len = String.length s in
match left_pos s len with
| Some i -> String.sub s i (len - i)
| None -> ""
let rtrim s =
let len = String.length s in
match right_pos s len with
| Some i -> String.sub s 0 (i + 1)
| None -> ""
we put the previous code in a file called "trim.ml", and then we test these functions in the toplevel:
$ ocaml # #use "trim.ml" ;; val left_pos : string -> int -> int option = <fun> val right_pos : string -> int -> int option = <fun> val trim : string -> string = <fun> val ltrim : string -> string = <fun> val rtrim : string -> string = <fun> # let s = " \t \r \n String with spaces \t \r \n " ;; val s : string = " \t \r \n String with spaces \t \r \n " # trim s ;; - : string = "String with spaces" # ltrim s ;; - : string = "String with spaces \t \r \n " # rtrim s ;; - : string = " \t \r \n String with spaces"
Since OCaml version 4.00.0 there is a function String.trim.
OpenEdge/Progress
DEF VAR cc AS CHAR INIT " string with spaces ".
MESSAGE
"|" + LEFT-TRIM( cc ) + "|" SKIP
"|" + RIGHT-TRIM( cc ) + "|" SKIP
"|" + TRIM( cc ) + "|"
VIEW-AS ALERT-BOX.
- Output:
--------------------------- Message --------------------------- |string with spaces | | string with spaces| |string with spaces| --------------------------- OK ---------------------------
PascalABC.NET
begin
var s := #9' abc '#9;
Writeln(s.TrimStart,'|');
Writeln(s.TrimEnd,'|');
Writeln(s.Trim,'|');
end.
- Output:
abc | abc| abc|
Perl
sub ltrim { shift =~ s/^\s+//r }
sub rtrim { shift =~ s/\s+$//r }
sub trim { ltrim rtrim shift }
# Usage:
my $p = " this is a string ";
print "'", $p, "'\n";
print "'", trim($p), "'\n";
print "'", ltrim($p), "'\n";
print "'", rtrim($p), "'\n";
Phix
with javascript_semantics constant s = "\t test \n" ?s ?trim_head(s) ?trim_tail(s) ?trim(s)
- Output:
"\t test \n" "test \n" "\t test" "test"
PHP
There is a built-in function that already does this.
<?php
/**
* @author Elad Yosifon
*/
$string = ' this is a string ';
echo '^'.trim($string) .'$'.PHP_EOL;
echo '^'.ltrim($string).'$'.PHP_EOL;
echo '^'.rtrim($string).'$'.PHP_EOL;
- Output:
^this is a string$ ^this is a string $ ^ this is a string$
Picat
Using the built-in functions lstrip/1
, rstrip/1
, strip/1
, and strip/2
.
import util.
go =>
S = " Jabberwocky ",
println("<" ++ S ++ ">"),
println("<" ++ lstrip(S) ++ ">"),
println("<" ++ rstrip(S) ++ ">"),
println("<" ++ strip(S) ++ ">"),
println("<" ++ strip("\t\r\bTwas brillig, and the slithy toves\r \t\v"," \b\v\t\r\v") ++ ">"),
nl.
- Output:
< Jabberwocky > <Jabberwocky > < Jabberwocky> <Jabberwocky> <Twas brillig, and the slithy toves>
PicoLisp
(de trimLeft (Str)
(pack (flip (trim (flip (chop Str))))) )
(de trimRight (Str)
(pack (trim (chop Str))) )
(de trimBoth (Str)
(pack (clip (chop Str))) )
Test:
: (trimLeft " ^G ^I trimmed left ^L ") -> "trimmed left ^L " : (trimRight " ^G ^I trimmed right ^L ") -> " ^G ^I trimmed right" : (trimBoth " ^G ^I trimmed both ^L ") -> "trimmed both"
PL/I
put ( trim(text, ' ', '') ); /* trims leading blanks. */
put ( trim(text, '', ' ') ); /* trims trailing blanks. */
put ( trim(text) ); /* trims leading and trailing */
/* blanks. */
To remove any white-space character(s) in a portable way:-
declare whitespace character(33) value
((substr(collate(), 1, 32) || ' '));
put ( trim(text, whitespace) ); /* trims leading white space. */
put ( trim(text, '', whitespace) ); /* trims trailing white space. */
put ( trim(text, whitespace, whitespace) );
/* trims leading and trailing */
/* white space. */
PL/I-80
PL/I-80 lacks the built-in trim function of its big brother, but the basic functionality is easy to implement.
trim_test: procedure options (main);
declare
test char(127) varying;
test = ' This is a test string ';
put skip edit ('orginal: |',test,'|') (a);
put skip edit ('ltrim : |',ltrim(test),'|') (a);
put skip edit ('rtrim : |',rtrim(test),'|') (a);
put skip edit ('trim : |',trim(test),'|') (a) ;
stop;
/* return s with leading white space removed */
ltrim: procedure (s) returns (char(127) varying);
declare
s char(127) varying,
(slen, i) fixed binary(15);
slen = length(s);
i = 1;
do while (i <= slen & substr(s,i,1) <= ' ');
i = i + 1;
end;
return (substr(s,i,slen));
end ltrim;
/* return s with trailing white space removed */
rtrim: procedure (s) returns (char(127) varying);
declare
s char(127) varying,
(slen, i) fixed binary(15);
slen = length(s);
i = slen;
do while (i >= 1 & substr(s,i,1) <= ' ');
i = i - 1;
end;
return (substr(s,1,i));
end rtrim;
/* return s with leading and trailing white space removed */
trim: procedure (s) returns (char(127) varying);
declare s char(127) varying;
return (ltrim(rtrim(s)));
end trim;
end trim_test;
- Output:
Original: | This is a test string | ltrim : | This is a test string| rtrim : |This is a test string | trim : |This is a test string|
PowerShell
$var = " Hello World "
$var.TrimStart() # String with leading whitespace removed
$var.TrimEnd() # String with trailing whitespace removed
$var.Trim() # String with both leading and trailing whitespace removed
Output:
Hello World Hello World Hello World
Prolog
Works with SWI-Prolog.
strip :-
In = " There are unwanted blanks here! ",
strip_left(In, OutLeft),
format('In : ~s__~n', [In]),
format('Strip left : ~s__~n', [OutLeft]),
strip_right(In, OutRight),
format('Strip right : ~s__~n', [OutRight]),
strip(In, Out),
format('Strip : ~s__~n', [Out]).
strip_left(In, Out) :-
strip_action(In, Out, []).
strip_right(In, Out) :-
reverse(In, RIn),
strip_left(RIn, ROut),
reverse(ROut, Out).
strip(In, Out) :-
strip_left(In, Tmp),
strip_right(Tmp, Out).
strip_action([X|T]) -->
{\+code_type(X, graph), !},
strip_action(T).
strip_action(X) --> X.
Output :
?- strip. In : There are unwanted blanks here! __ Strip left : There are unwanted blanks here! __ Strip right : There are unwanted blanks here!__ Strip : There are unwanted blanks here!__ true.
SWI-Prolog has an integrated version of strip : normalize_space(-Out, +In)
?- In = ' There are unwanted blanks here! ', normalize_space(atom(Out), In). In = ' There are unwanted blanks here! ', Out = 'There are unwanted blanks here!'.
alternative using DCG strings
:- system:set_prolog_flag(double_quotes,chars) .
strip_leading(INPUTz,OUTPUTz)
:-
prolog:phrase(strip_leading(OUTPUTz),INPUTz)
.
strip_trailing(INPUTz,OUTPUTz)
:-
prolog:phrase(strip_trailing(OUTPUTz),INPUTz)
.
strip_leading_and_trailing(INPUTz,OUTPUTz)
:-
prolog:phrase(strip_leading_and_trailing(OUTPUTz),INPUTz)
.
strip_leading(OUTPUTz)
-->
strip_leading_spacious ,
strip_leading_nonspacious(OUTPUTz)
.
strip_trailing(OUTPUTz)
-->
strip_trailing_nonspacious(OUTPUTz) ,
strip_trailing_spacious
.
strip_leading_and_trailing(OUTPUTz)
-->
strip_leading_spacious ,
strip_trailing_nonspacious(OUTPUTz) ,
strip_trailing_spacious
.
strip_leading_spacious
-->
[CHAR] ,
{ prolog:char_type(CHAR,space) } ,
! ,
strip_leading_spacious
.
strip_leading_spacious
-->
[]
.
strip_leading_nonspacious([OUTPUT|OUTPUTz])
-->
[OUTPUT] ,
! ,
strip_leading_nonspacious(OUTPUTz)
.
strip_leading_nonspacious([])
-->
[]
.
strip_trailing_nonspacious([OUTPUT|OUTPUTz])
-->
\+ strip_trailing_spacious ,
[OUTPUT] ,
! ,
strip_trailing_nonspacious(OUTPUTz)
.
strip_trailing_nonspacious([])
-->
[]
.
strip_trailing_spacious
-->
[CHAR] ,
{ prolog:char_type(CHAR,space) } ,
! ,
strip_trailing_spacious
.
strip_trailing_spacious
-->
\+ [_] % .i.e. at end-of-string .
.
- Output:
/* ?- strip_leading(" Hello World ",OUTPUTz) . OUTPUTz = ['H', e, l, l, o, ' ', 'W', o, r, l, d, ' ']. ?- strip_trailing(" Hello World ",OUTPUTz). OUTPUTz = [' ', 'H', e, l, l, o, ' ', 'W', o, r, l, d]. ?- strip_leading_and_trailing(" Hello World ",OUTPUTz). OUTPUTz = ['H', e, l, l, o, ' ', 'W', o, r, l, d]. ?-
PureBasic
Note, if only spaces need to be removed, PureBasic provides commands that do this: LTrim(), RTrim(), and Trim(). To handle a larger selection of whitespace the following functions meet the task.
;define the whitespace as desired
#whitespace$ = " " + Chr($9) + Chr($A) + Chr($B) + Chr($C) + Chr($D) + Chr($1C) + Chr($1D) + Chr($1E) + Chr($1F)
Procedure.s myLTrim(source.s)
Protected i, *ptrChar.Character, length = Len(source)
*ptrChar = @source
For i = 1 To length
If Not FindString(#whitespace$, Chr(*ptrChar\c))
ProcedureReturn Right(source, length + 1 - i)
EndIf
*ptrChar + SizeOf(Character)
Next
EndProcedure
Procedure.s myRTrim(source.s)
Protected i, *ptrChar.Character, length = Len(source)
*ptrChar = @source + (length - 1) * SizeOf(Character)
For i = length To 1 Step - 1
If Not FindString(#whitespace$, Chr(*ptrChar\c))
ProcedureReturn Left(source, i)
EndIf
*ptrChar - SizeOf(Character)
Next
EndProcedure
Procedure.s myTrim(source.s)
ProcedureReturn myRTrim(myLTrim(source))
EndProcedure
If OpenConsole()
PrintN(#DQUOTE$ + myLTrim(" Top ") + #DQUOTE$)
PrintN(#DQUOTE$ + myRTrim(" Tail ") + #DQUOTE$)
PrintN(#DQUOTE$ + myTrim(" Both ") + #DQUOTE$)
Print(#CRLF$ + #CRLF$ + "Press ENTER to exit"): Input()
CloseConsole()
EndIf
- Output:
"Top " " Tail" "Both"
Python
>>> s = ' \t \r \n String with spaces \t \r \n '
>>> s
' \t \r \n String with spaces \t \r \n '
>>> s.lstrip()
'String with spaces \t \r \n '
>>> s.rstrip()
' \t \r \n String with spaces'
>>> s.strip()
'String with spaces'
>>>
Quackery
As a dialogue in the Quackery shell.
/O> [ reverse trim reverse ] is trim-trailing ( $ --> $ )
... [ trim trim-trailing ] is trim-both-ends ( $ --> $ )
... $ ' a quick quack ' echo$ say "!" cr
... $ ' a quick quack ' trim echo$ say "!" cr
... $ ' a quick quack ' trim-trailing echo$ say "!" cr
... $ ' a quick quack ' trim-both-ends echo$ say "!" cr
...
a quick quack !
a quick quack !
a quick quack!
a quick quack!
Stack empty.
R
s <- " Ars Longa "
trimws(s)
[1] "Ars Longa"
trimws(s, "left")
[1] "Ars Longa "
trimws(s, "right")
[1] " Ars Longa"
Racket
#lang racket
;; Using Racket's `string-trim'
(define str " \n\t foo bar \r\n ")
;; both sides:
(string-trim str) ; -> "foo bar"
;; one side:
(string-trim str #:right? #f) ; -> "foo bar \r\n "
(string-trim str #:left? #f) ; -> " \n\t foo bar"
;; can also normalize spaces:
(string-normalize-spaces (string-trim str)) ; -> "foo bar"
Raku
(formerly Perl 6)
my $s = "\r\n \t\x2029 Good Stuff \x202F\n";
say $s.trim;
say $s.trim.raku;
say $s.trim-leading.raku;
say $s.trim-trailing.raku;
- Output:
Good Stuff "Good Stuff" "Good Stuff \n" "\r\n \t Good Stuff"
Red
>> trim/head " remove leading white space "
== "remove leading white space "
>> trim/tail " remove trailing white space "
== " remove trailing white space"
>> trim " remove both white spaces "
== "remove both white spaces"
Retro
'__this_is_a_test___ s:trim-left
'__this_is_a_test___ s:trim-right
'__this_is_a_test___ s:trim
REXX
version 1
/*REXX program demonstrates how to strip leading and/or trailing spaces (blanks). */
yyy=" this is a string that has leading/embedded/trailing blanks, fur shure. "
say 'YYY──►'yyy"◄──" /*display the original string + fence. */
/*white space also includes tabs (VT, HT), among other characters.*/
/*all examples in each group are equivalent, only the option's 1st*/
/*character is examined. */
noL=strip(yyy,'L') /*elide any leading white space. */
noL=strip(yyy,"l") /* (the same as the above statement.) */
noL=strip(yyy,'leading') /* " " " " " " */
say 'noL──►'noL"◄──" /*display the string with a title+fence*/
noT=strip(yyy,'T') /*elide any trailing white space. */
noT=strip(yyy,"t") /* (the same as the above statement.) */
noT=strip(yyy,'trailing') /* " " " " " " */
say 'noT──►'noT"◄──" /*display the string with a title+fence*/
noB=strip(yyy) /*elide leading & trailing white space.*/
noB=strip(yyy,) /* (the same as the above statement.) */
noB=strip(yyy,'B') /* " " " " " " */
noB=strip(yyy,"b") /* " " " " " " */
noB=strip(yyy,'both') /* " " " " " " */
say 'noB──►'noB"◄──" /*display the string with a title+fence*/
/*elide leading & trailing white space,*/
noX=space(yyy) /* including white space between words.*/
say 'nox──►'noX"◄──" /*display the string with a title+fence*/
/*stick a fork in it, we're all done. */
output
YYY──► this is a string that has leading/embedded/trailing blanks, fur shure. ◄── noL──►this is a string that has leading/embedded/trailing blanks, fur shure. ◄── noT──► this is a string that has leading/embedded/trailing blanks, fur shure.◄── noB──►this is a string that has leading/embedded/trailing blanks, fur shure.◄── nox──►this is a string that has leading/embedded/trailing blanks, fur shure.◄──
version 2
/* REXX ***************************************************************
* 01.1.2012 Walter Pachl taking care of all non-printable chars
**********************************************************************/
pc='abcdefghijklmnopqrstuvwxyz'
pc=pc||translate(pc)'äöüÄÖÜß1234567890!"§&/()=?*+''#;:_,.-<>^!'
x01='01'x
s=x01||' Hi '||x01||' there! '||x01
say pc /* all printable characters */
s=x01||' Hi '||x01||' there! '||x01 /* my source string */
Say 's >'s'<' /* show it */
p1=verify(s,pc,'M') /* find first printable char */
sl=substr(s,p1) /* start with it */
Say 'sl>'sl'<'
sr=reverse(s)
p2=verify(sr,pc,'M') /* find last printable char */
sr=left(s,length(s)-p2+1) /* end with it */
Say 'sr>'sr'<'
sb=substr(s,p1,length(s)-p1-p2+1) /* remove leading & trailing */
Say 'sb>'space(sb)'!' /* whitespace */
sa=translate(s,pc,pc!!xrange('00'x,'FF'x)) /* all nonprintable chars */
/* are translated to blanks */
sa=space(sa) /* eliminate them except 1 */
Say 'sa>'sa'<'<' /* between words */
s0=space(sa,0) /* remove all whitespace */
Say 's0>'s0'<'
Output:
abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZäöüÄÖÜß1234567890!"§&/()=?*+'#;:_,.-<>^! s >� Hi � there! �< sl>Hi � there! �< sr>� Hi � there!< sb>Hi � there!< sa>Hi there!< s0>Hithere!<
Ring
aList = " Welcome to the Ring Programming Language "
see aList + nl
see trim(aList) + nl
RPL
Recursivity provides short code.
≪ IF DUP 1 1 SUB " " == THEN 2 OVER SIZE SUB TRIM END IF DUP DUP SIZE DUP SUB " " == THEN 1 OVER SIZE 1 - SUB TRIM END ≫ ‘TRIM’ STO
" What if true luxury was space? " TRIM
- Output:
1: "What if true luxury was space?"
Ruby
s = " \t\v\r\n\ffoo bar \t\v\r\n\f"
p s
p s.lstrip # remove leading whitespaces
p s.rstrip # remove trailing whitespaces
p s.strip # remove both leading and trailing whitespace
- Output:
" \t\v\r\n\ffoo bar \t\v\r\n\f" "foo bar \t\v\r\n\f" " \t\v\r\n\ffoo bar" "foo bar"
Run BASIC
string$ = " abcdefg "
print " Top:";trim$(string$+"|") ' top left trim
print "Bottom:";trim$("|"+string$) ' bottom right trim
print " Both:";trim$(string$) ' both left and right
end
Top:abcdefg Bottom: abcdefg Both:abcdefg
Rust
fn main() {
let spaces = " \t\n\x0B\x0C\r \u{A0} \u{2000}\u{3000}";
let string_with_spaces = spaces.to_owned() + "String without spaces" + spaces;
assert_eq!(string_with_spaces.trim(), "String without spaces");
assert_eq!(string_with_spaces.trim_left(), "String without spaces".to_owned() + spaces);
assert_eq!(string_with_spaces.trim_right(), spaces.to_owned() + "String without spaces");
}
Sather
class MAIN is
ltrim(s :STR) :STR is
i ::= 0;
loop while!(i < s.size);
if " \t\f\v\n".contains(s[i]) then
i := i + 1;
else
break!;
end;
end;
return s.tail(s.size - i);
end;
rtrim(s :STR) :STR is
i ::= s.size-1;
loop while!(i >= 0);
if " \t\f\v\n".contains(s[i]) then
i := i - 1;
else
break!;
end;
end;
return s.head(i+1);
end;
trim(s :STR) :STR is
return ltrim(rtrim(s));
end;
main is
p ::= " this is a string ";
#OUT + ltrim(p).pretty + "\n";
#OUT + rtrim(p).pretty + "\n";
#OUT + trim(p).pretty + "\n";
end;
end;
S-BASIC
S-BASIC has no built-in functions for the task, but it's easy enough to write our own.
rem - remove leading white space from s
function ltrim(s = string) = string
var i, slen = integer
i = 1
slen = len(s)
while i <= slen and mid(s, i, 1) <= " " do
i = i + 1
end = right(s,i)
rem - remove trailing white space from s
function rtrim(s = string) = string
var i, slen = integer
slen = len(s)
i = slen
while i > 0 and mid(s, i, 1) <= " " do
i = i - 1
end = left$(s, i)
rem - remove leading and trailing white space from s
function trim(s = string) = string
end = ltrim(rtrim(s))
rem - exercise the functions
var test = string
test = " This is the test string "
print "original: |"; test; "|"
print "trim : |"; trim(test); "|"
print "rtrim : |"; rtrim(test); "|"
print "ltrim : |"; ltrim(test); "|"
end
- Output:
original: | This is the test string | trim : |This is the test string| rtrim : | This is the test string| ltrim : |This is the test string |
Scala
def trimLeft(str: String) = str dropWhile(_.isWhitespace)
def trimRight(str: String) = str take (str.lastIndexWhere(!_.isWhitespace) + 1)
def trimRight2(str: String) = trimLeft(str reverse) reverse
def trim(str: String) = str trim
def testTrim() = {
val str = " \u001F String with spaces \t \n \r "
println("original : |" + str + "|")
println("trimLeft : |" + trimLeft(str) + "|")
println("trimRight : |" + trimRight(str) + "|")
println("trimRight2: |" + trimRight2(str) + "|")
println("trim : |" + trim(str) + "|")
}
- Output:
original : | � String with spaces | trimLeft : |String with spaces | trimRight : | � String with spaces| trimRight2: | � String with spaces| trim : |String with spaces|
Seed7
$ include "seed7_05.s7i";
const proc: main is func
local
const string: testStri is " \t \r \n String with spaces \t \r \n ";
begin
writeln(ltrim(testStri));
writeln(rtrim(testStri));
writeln(trim(testStri));
end func;
Sidef
var s = " \t\v\r\n\ffoo bar \t\v\r\n\f";
say s.strip_beg.dump; # remove leading whitespaces
say s.strip_end.dump; # remove trailing whitespaces
say s.strip.dump; # remove both leading and trailing whitespace
- Output:
"foo bar \t\13\r\n\f" " \t\13\r\n\ffoo bar" "foo bar"
Smalltalk
String extend
[
ltrim [
^self replacingRegex: '^\s+' with: ''.
]
rtrim [
^self replacingRegex: '\s+$' with: ''.
]
trim [
^self ltrim rtrim.
]
]
|a|
a := ' this is a string '.
('"%1"' % {a}) displayNl.
('"%1"' % {a ltrim}) displayNl.
('"%1"' % {a rtrim}) displayNl.
('"%1"' % {a trim}) displayNl.
SNOBOL4
s1 = s2 = " Hello, people of earth! "
s2 = CHAR(3) s2 CHAR(134)
&ALPHABET TAB(33) . prechars
&ALPHABET POS(127) RTAB(0) . postchars
stripchars = " " prechars postchars
* TRIM() removes final spaces and tabs:
OUTPUT = "Original: >" s1 "<"
OUTPUT = "With trim() >" REVERSE(TRIM(REVERSE(TRIM(s1)))) "<"
* Remove all non-printing characters:
OUTPUT = "Original: >" s2 "<"
s1 POS(0) SPAN(stripchars) =
OUTPUT = "Leading: >" s1 "<"
s2 ARB . s2 SPAN(stripchars) RPOS(0)
OUTPUT = "Trailing: >" s2 "<"
s2 POS(0) SPAN(stripchars) =
OUTPUT = "Full trim: >" s2 "<"
END
- Output:
Original: > Hello, people of earth! < With trim() >Hello, people of earth!< Original: >� Hello, people of earth! �< Leading: >Hello, people of earth! < Trailing: >� Hello, people of earth!< Full trim: >Hello, people of earth!<
Standard ML
local
open Substring
in
val trimLeft = string o dropl Char.isSpace o full
and trimRight = string o dropr Char.isSpace o full
and trim = string o dropl Char.isSpace o dropr Char.isSpace o full
end
Stata
See strtrim in Stata help. Use the equivalent ustrtrim functions with Unicode strings.
s = " ars longa "
"("+strtrim(s)+")"
(ars longa)
"("+strltrim(s)+")"
(ars longa )
"("+strrtrim(s)+")"
( ars longa)
"("+stritrim(s)+")"
( ars longa )
Tcl
Whitespace stripping is done with string trim
and related commands:
set str " hello world "
puts "original: >$str<"
puts "trimmed head: >[string trimleft $str]<"
puts "trimmed tail: >[string trimright $str]<"
puts "trimmed both: >[string trim $str]<"
- Output:
original: > hello world < trimmed head: >hello world < trimmed tail: > hello world< trimmed both: >hello world<
TI-83 BASIC
PROGRAM:WHITESPC
Input Str1
0→M
Menu(" REMOVE ","TRAILIN WHTSPC",A,"LEADING WHTSPC",C,"BOTH",B)
Lbl B
1→M
Lbl A
While sub(Str1,length(Str1)-1),1)=" "
sub(Str1,1,length(Str1)-1)→Str1
End
If M=1
Then
Goto C
Else
Goto F
End
Lbl C
While sub(str1,1,1)=" "
sub(Str1,2,length(Str1)-1)→Str1
End
Lbl F
Disp "'"+Str1+"'"
TorqueScript
Remove leading whitespace
$string = " yep "; $string = LTrim($string); echo($string);
Remove trailing whitespace
$string = " yep "; $string = RTrim($string); echo($string);
Remove leading and trailing white spaces
$string = " yep "; $string = trim($string); echo($string);
Output
"yep " " yep" "yep"
True BASIC
LET s$ = " \tRosetta Code \v\f\r\n"
PRINT ltrim$(s$) ! remove leading whitespace
PRINT rtrim$(s$) ! remove trailing whitespace
PRINT trim$(s$) ! remove both leading and trailing whitespace
END
TUSCRIPT
$$ MODE TUSCRIPT
str= " sentence w/whitespace before and after "
trimmedtop=EXTRACT (str,":<|<> :"|,0)
trimmedtail=EXTRACT (str,0,":<> >|:")
trimmedboth=SQUEEZE(str)
PRINT "string <|", str," >|"
PRINT "trimmed on top <|",trimmedtop,">|"
PRINT "trimmed on tail <|", trimmedtail,">|"
PRINT "trimmed on both <|", trimmedboth,">|"
- Output:
string <| sentence w/whitespace before and after >| trimmed on top <|sentence w/whitespace before and after >| trimmed on tail <| sentence w/whitespace before and after>| trimmed on both <|sentence w/whitespace before and after>|
TXR
Pattern Matching Language Exercise
Here, no builtin functions are used, just text pattern matching logic. Two functions are written, conforming to the proper filter convention, and then employed as filters.
@(define trim_left (in out))
@ (next :list in)
@/[ \t]*/@out
@(end)
@(define trim_right (in out))
@ (local blanks middle)
@ (next :list in)
@ (cases)
@ {blanks /[ \t]*/}@middle@/[\t ]+/
@ (bind out `@blanks@middle`)
@ (or)
@ out
@ (end)
@(end)
@line_of_input
@(output)
trim-left: [@{line_of_input :filter (:fun trim_left)}]
trim_right: [@{line_of_input :filter (:fun trim_right)}]
trim_both: [@{line_of_input :filter ((:fun trim_left) (:fun trim_right))}]
@(end)
- Output:
$ echo "" | txr trim.txr - trim-left: [] trim_right: [] trim_both: [] $ echo "a" | txr trim.txr - trim-left: [a] trim_right: [a] trim_both: [a] $ echo " a" | txr trim.txr - trim-left: [a] trim_right: [ a] trim_both: [a] $ echo " a " | txr trim.txr - trim-left: [a ] trim_right: [ a] trim_both: [a] $ echo " a b " | txr trim.txr - trim-left: [a b ] trim_right: [ a b] trim_both: [a b]
Using Lisp Primitives
Trimming whitespace from both ends is a builtin:
$ txr -p '(trim-str " a b ")'
"a b"
An unnecessarily cryptic, though educational, left trim:
$ txr -p '[(do progn (del [@1 0..(match-regex @1 #/\s*/)]) @1) " a b "]'
"a b "
Explanation: the basic structure is [function " a b "]
where the function is an anonymous lambda generated using the do
operator. The function is applied to the string " a b "
.
The structure of the do
is (do progn (blah @1) @1)
where the forms make references to implicit argument @1
, and so the generated lambda has one argument, essentially being: (lambda (arg) (blah arg) arg)
: do something with the argument (the string) and then return it.
What is done with the argument is this: (del [@1 0..(match-regex @1 #/\s+/)])
. The match-regex
function returns the number of characters at the front of the string which match the regex \s*
: one or more spaces. The return value of this is used to express a range 0..length
which is applied to the string. The syntax (del [str from..to])
deletes a range of characters in the string.
Lastly, a pedestrian right trim:
(defun trim-right (str)
(for ()
((and (> (length str) 0) (chr-isspace [str -1])) str)
((del [str -1]))))
(format t "{~a}\n" (trim-right " a a "))
(format t "{~a}\n" (trim-right " "))
(format t "{~a}\n" (trim-right "a "))
(format t "{~a}\n" (trim-right ""))
Output:
{ a a} {} {a} {}
Ursala
#import std
white = ==` !| not @iNC %sI
trim_left = white-~r
trim_right = white~-l
trim_both = trim_left+ trim_right
#cast %sgUL
main = <.trim_left,trim_right,trim_both> ' string with spaces '
- The
white
predicate tests an argument for whiteness by either comparing it to a literal space character or testing whether the singleton list containing it is of a string (%s
) type. - The
-~
postfix operator takes a predicate to a function that takes a string to a pair of strings whose concatenation is the original string and whose left side is the maximal prefix of the original string whose members satisfy the predicate. - The
r
suffix on the-~
predicate extracts the right side of the pair of strings in the result. - The
~-
operator is similar to the-~
operator except that is concerned with the maximal suffix whose members satisfy the predicate. - The
l
suffix extracts the right side.
- Output:
< 'string with spaces ', ' string with spaces', 'string with spaces'>
Vala
Strip Leading White Space
string s = " word ";
string s_chug = s.chug();
Strip Trailing White Space
string s = " word ";
string s_chomp = s.chomp();
Strip Leading & Trailing White Space
string s = " word ";
string s_strip = s.strip();
VBA
Public Sub test()
'LTrim trims leading spaces
'RTrim trims tailing spaces
'Trim trims both leading and tailing spaces
s = " trim "
Debug.Print """" & s & """"
Debug.Print """" & LTrim(s) & """"
Debug.Print """" & RTrim(s) & """"
Debug.Print """" & WorksheetFunction.trim(s) & """"
'these functions do not remove tabs or newlines
End Sub
- Output:
" trim " "trim " " trim" "trim"
VBScript
Function LeftTrim(s)
Set regex = New RegExp
With regex
.Pattern = "^\s*"
If .Test(s) Then
LeftTrim = .Replace(s,"")
Else
LeftTrim = s
End If
End With
End Function
Function RightTrim(s)
Set regex = New RegExp
With regex
.Pattern = "\s*$"
If .Test(s) Then
RightTrim = .Replace(s,"")
Else
RightTrim = s
End If
End With
End Function
'testing the functions
WScript.StdOut.WriteLine LeftTrim(" RosettaCode")
WScript.StdOut.WriteLine RightTrim("RosettaCode ")
WScript.StdOut.WriteLine LeftTrim(RightTrim(" RosettaCode "))
- Output:
RosettaCode RosettaCode RosettaCode
Wren
In Wren 'whitespace' is defined as: space, tab, carriage return, and line feed characters. To trim off other non-printing characters such as form feed and vertical tab, you need to do a little more work.
var a = " \t\r\nString with leading whitespace removed"
var b = "String with trailing whitespace removed \t\r\n"
var c = " \t\r\nString with both leading and trailing whitespace removed \t\r\n"
var d = " \t\r\n\f\vString with leading whitespace, form feed and verical tab characters removed"
System.print("'%(a.trimStart())'")
System.print("'%(b.trimEnd())'")
System.print("'%(c.trim())'")
System.print("'%(d.trimStart(" \t\r\n\f\v"))'") // similar overloads of trimEnd and trim exist
- Output:
'String with leading whitespace removed' 'String with trailing whitespace removed' 'String with both leading and trailing whitespace removed' 'String with leading whitespace, form feed and vertical tab characters removed'
XBasic
PROGRAM "progname"
VERSION "0.0000"
DECLARE FUNCTION Entry ()
FUNCTION Entry ()
s$ = " \tRosetta Code \v\f\r\n"
PRINT LTRIM$(s$) ' remove leading whitespace
PRINT RTRIM$(s$) ' remove trailing whitespace
PRINT TRIM$(s$) ' remove both leading and trailing whitespace
END FUNCTION
END PROGRAM
XPL0
code ChOut=8, CrLf=9, Text=12;
string 0; \use zero-terminated string convention
func StripLead(S0); \Strip leading whitespace (<=$20) from string
char S0;
char S1(80); \BEWARE: very temporary string space returned
int I, J, C, Stripped;
[I:= 0; J:= 0; Stripped:= false;
repeat C:= S0(I); I:= I+1;
if Stripped ! C>$20 ! C=0 then
[S1(J):= C; J:= J+1; Stripped:= true];
until C=0;
return S1;
];
func StripTrail(S0); \Strip trailing whitespace (<=$20) from string
char S0;
char S1(80); \BEWARE: very temporary string space returned
int I, SI;
[I:= 0;
loop [if S0(I) <= $20 then
[SI:= I;
while S0(I) <= $20 do
[if S0(I) = 0 then [S1(SI):= 0; return S1];
S1(I):= S0(I); I:= I+1;
];
]
else [S1(I):= S0(I); I:= I+1];
];
];
char String;
[String:= " Hello World ";
Text(0, StripLead(String)); ChOut(0, ^!); CrLf(0);
Text(0, StripTrail(String)); ChOut(0, ^!); CrLf(0);
Text(0, StripTrail(StripLead(String))); ChOut(0, ^!); CrLf(0);
]
Output:
Hello World ! Hello World! Hello World!
Yabasic
s$ = "\t test \n"
print "--",ltrim$(s$),"--"
print "--",rtrim$(s$),"--"
print "--",trim$(s$),"--"
zkl
Remove white space from both end of string:
"\t\n hoho\n\t\ ".strip() //-->"hoho"
fcn removeLeadingWS(s){ n:=0;
try{ while(s[n].isSpace()){ n+=1 } }catch{""}fallthrough{ s[n,*] }
}
removeLeadingWS("\t\n hoho\n\t\ ") //-->"hoho\n\t "
removeLeadingWS("") //-->""
fcn removeTrailingWS(s){ n:=-1;
try{ while(s[n].isSpace()){ n-=1 } s[0,n+1] }catch{""}
}
removeTrailingWS("\t\n hoho\n\t\ ") //-->"\t\n hoho"
removeTrailingWS("\t\n \n\t\ ") //-->""
Zoea
program: trim_left
input: ' abcd'
output: 'abcd'
program: trim_right
input: 'abcd '
output: 'abcd'
program: trim
input: ' abcd '
output: 'abcd'
Zoea Visual
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