Comparison of programming languages (string functions)

String functions are used in computer programming languages to manipulate a string or query information about a string (some do both).

Most programming languages that have a string datatype will have some string functions although there may be other low-level ways within each language to handle strings directly. In object-oriented languages, string functions are often implemented as properties and methods of string objects. In functional and list-based languages a string is represented as a list (of character codes), therefore all list-manipulation procedures could be considered string functions. However such languages may implement a subset of explicit string-specific functions as well.

For function that manipulate strings, modern object-oriented languages, like C# and Java have immutable strings and return a copy (in newly allocated dynamic memory), while others, like C manipulate the original string unless the programmer copies data to a new string. See for example Concatenation below.

The most basic example of a string function is the length(string) function. This function returns the length of a string literal.

e.g. length("hello world") would return 11.

Other languages may have string functions with similar or exactly the same syntax or parameters or outcomes. For example, in many languages the length function is usually represented as len(string). The below list of common functions aims to help limit this confusion.

Common string functions (multi language reference)

String functions common to many languages are listed below, including the different names used. The below list of common functions aims to help programmers find the equivalent function in a language. Note, string concatenation and regular expressions are handled in separate pages. Statements in guillemets (« … ») are optional.

CharAt

Definition	charAt(string,integer) returns character.
Description	Returns character at index in the string.
Equivalent	See substring of length 1 character.

Format	Languages	Base index
string[i]	ALGOL 68, Pascal, Object Pascal (Delphi), Seed7	1
string[i]	C, C++, C#, Cobra, D, FreeBASIC, Go, Python,[1] PHP, Ruby,[1] Windows PowerShell, JavaScript, Ya	0
string{i}	PHP (deprecated in 5.3)	0
string(i)	Ada	≥1
Mid(string,i,1)	VB	1
MID$(string,i,1)	BASIC	1
string.Chars(i)	VB.NET	0
string(i:i)	Fortran	1
string.charAt(i)	Java, JavaScript	0
string.[i]	OCaml, F#	0
String.sub (string, i)	Standard ML	0
string !! i	Haskell	0
(string-ref string i)	Scheme	0
(char string i)	Common Lisp	0
(elt string i)	ISLISP	0
(get string i)	Clojure	0
substr(string, i, 1)	Perl[1]	0
substr(string, i, 1)	PL/I	1
string.at(i)	C++ (STL) (w/ bounds checking)	0
lists:nth(i, string)	Erlang	1
[string characterAtIndex:i]	Objective-C (NSString * only)	0
string.sub(string, i, i) (string):sub(i, i)	Lua[1]	1
string at: i	Smalltalk (w/ bounds checking)	1
string index string i	Tcl	0
StringTake[string, {i}]	Mathematica, Wolfram Language[1]	1
string@i	Eiffel	1
string (i:1)	COBOL	1

{ Example in Pascal }
var 
  MyStr: string = 'Hello, World';
  MyChar: Char;
begin
  MyChar := MyStr[2];         // 'e'

# Example in ALGOL 68 #
"Hello, World"[2];         // 'e'

// Example in C# and Ya
"Hello, World"[2];         // 'l'

# Examples in Python
"Hello, World"[2]          #  'l'
"Hello, World"[-3]         #  'r'

' Example in Visual Basic
Mid("Hello, World",2,1)

' Example in Visual Basic .NET
"Hello, World".Chars(2)    '  "l"c

" Example in Smalltalk "
'Hello, World' at: 2.    "$e"

Compare (integer result)

Definition

compare(string1,string2) returns integer.

Description

Compares two strings to each other. If they are equivalent, a zero is returned. Otherwise, most of these routines will return a positive or negative result corresponding to whether string1 is lexicographically greater than, or less than, respectively, than string2. The exceptions are the Scheme and Rexx routines which return the index of the first mismatch, and Smalltalk which answer a comparison code telling how the receiver sorts relative to string parameter.

Format	Languages
IF string1<string2 THEN -1 ELSE ABS (string1>string2) FI	ALGOL 68
cmp(string1, string2)	Python 2
(string1 > string2) - (string1 < string2)	Python
strcmp(string1, string2)	C, PHP
std.string.cmp(string1, string2)	D
StrComp(string1, string2)	VB, Object Pascal (Delphi)
string1 cmp string2	Perl
string1 compare: string2	Smalltalk (Squeak, Pharo)
string1 <=> string2	Ruby
string1.compare(string2)	C++ (STL), Swift (Foundation)
compare(string1, string2)	Rexx, Seed7
CompareStr(string1, string2)	Pascal, Object Pascal (Delphi)
string1.compareTo(string2)	Cobra, Java
string1.CompareTo(string2)	VB .NET, C#, F#
(compare string1 string2)	Clojure
(string= string1 string2)	Common Lisp
(string-compare string1 string2 p< p= p>)	Scheme (SRFI 13)
(string= string1 string2)	ISLISP
compare string1 string2	OCaml
String.compare (string1, string2)	Standard ML [2]
compare string1 string2	Haskell [3]
[string]::Compare(string1, string2)	Windows PowerShell
[string1 compare:string2]	Objective-C (NSString * only)
LLT(string1,string2) LLE(string1,string2) LGT(string1,string2) LGE(string1,string2)	Fortran [4]
string1.localeCompare(string2)	JavaScript
bytes.Compare([]byte(string1), []byte(string2))	Go
string compare ?-nocase? ?-length int? string1 string2	Tcl
compare(string1,string2,count)	PL/I[5]

# Example in Python
cmp("hello", "world")      # returns -1

/** Example in Rexx */ 
compare("hello", "world")  /* returns index of mismatch: 1 */

; Example in Scheme
(use-modules (srfi srfi-13))
; returns index of mismatch: 0
(string-compare "hello" "world" values values values)

Compare (relational operator-based, Boolean result)

Definition	string1 OP string2 OR (compare string1 string2) returns Boolean.
Description	Lexicographically compares two strings using a relational operator or function. Boolean result returned.

Format	Languages
string1 OP string2, where OP can be any of =, <>, <, >, <= and >=	Pascal, Object Pascal (Delphi), OCaml, Seed7, Standard ML, BASIC, VB, VB .NET, F#
string1 OP string2, where OP can be any of =, /=, ≠, <, >, <=, ≤ and ≥; Also: EQ, NE, LT, LE, GE and GT	ALGOL 68
(stringOP? string1 string2), where OP can be any of =, -ci=, <, -ci<, >, -ci>, <=, -ci<=, >= and -ci>= (operators starting with '-ci' are case-insensitive)	Scheme
(stringOP string1 string2), where OP can be any of =, -ci=, <>, -ci<>, <, -ci<, >, -ci>, <=, -ci<=, >= and -ci>= (operators starting with '-ci' are case-insensitive)	Scheme (SRFI 13)
(stringOP string1 string2), where OP can be any of =, -equal, /=, -not-equal, <, -lessp, >, -greaterp, <=, -not-greaterp, >= and -not-lessp (the verbal operators are case-insensitive)	Common Lisp
(stringOP string1 string2), where OP can be any of =, /=, <, >, <=, and >=	ISLISP
string1 OP string2, where OP can be any of =, \=, <, >, <= and >=	Rexx
string1 OP string2, where OP can be any of =, ¬=, <, >, <=, >=, ¬< and ¬>	PL/I
string1 OP string2, where OP can be any of =, /=, <, >, <= and >=	Ada
string1 OP string2, where OP can be any of ==, /=, <, >, =< and >=	Erlang
string1 OP string2, where OP can be any of ==, /=, <, >, <= and >=	Haskell
string1 OP string2, where OP can be any of eq, ne, lt, gt, le and ge	Perl
string1 OP string2, where OP can be any of ==, !=, <, >, <= and >=	C++ (STL), C#, D, Go, JavaScript, Python, PHP, Ruby, Swift, Ya
string1 OP string2, where OP can be any of -eq, -ceq, -ne, -cne, -lt, -clt, -gt, -cgt, -le, -cle, -ge, and -cge (operators starting with 'c' are case-sensitive)	Windows PowerShell
string1 OP string2, where OP can be any of ==, ~=, <, >, <= and >=	Lua
string1 OP string2, where OP can be any of =, ~=, <, >, <= and >=	Smalltalk
string1 OP string2, where OP can be any of ==, /=, <, >, <= and >=; Also: .EQ., .NE., .LT., .LE., .GT. and .GE.	Fortran.[6]
string1 OP string2 where OP can be any of =, <>, <, >, <=, >= as well as worded equivalents	COBOL
string1 OP string2 where OP can be any of ==, <>, <, >, <= and >=	Cobra
string1 OP string2 is available in the syntax, but means comparison of the pointers pointing to the strings, not of the string contents. Use the Compare (integer result) function.	C, Java

% Example in Erlang
"hello" > "world".            % returns false

# Example in Windows PowerShell
"hello" -gt "world"           # returns false

;; Example in Common Lisp
(string> "art" "painting")      ; returns nil
(string< "art" "painting")      ; returns non nil

Concatenation

Definition	concatenate(string1,string2) returns string.
Description	Concatenates (joins) two strings to each other, returning the combined string. Note that some languages like C have mutable strings, so really the second string is being appended to the first string and the mutated string is returned.

Format	Languages
string1 & string2	Ada, FreeBASIC, Seed7, BASIC, VB, VB .NET, COBOL (between literals only)
strcat(string1, string2)	C, C++ (char * only)[7]
string1 . string2	Perl, PHP
string1 + string2	ALGOL 68, C++ (STL), C#, Cobra, FreeBASIC, Go, Pascal, Object Pascal (Delphi), Java, JavaScript, Windows PowerShell, Python, Ruby, Rust, F#, Swift, Turing, VB, Ya
string1 ~ string2	D
(string-append string1 string2)	Scheme, ISLISP
(concatenate 'string string1 string2)	Common Lisp
(str string1 string2)	Clojure
string1 || string2	Rexx, SQL, PL/I
string1 // string2	Fortran
string1 ++ string2	Erlang, Haskell
string1 ^ string2	OCaml, Standard ML, F#
[string1 stringByAppendingString:string2]	Objective-C (NSString * only)
string1 .. string2	Lua
string1 , string2	Smalltalk
string1 string2	SNOBOL
string1string2	Bash shell
string1 <> string2	Mathematica
concat string1 string2	Tcl

{ Example in Pascal }
'abc' + 'def';      // returns "abcdef"

// Example in C#
"abc" + "def";      // returns "abcdef"

' Example in Visual Basic
"abc" & "def"       '  returns "abcdef"
"abc" + "def"       '  returns "abcdef"
"abc" & Null        '  returns "abc"
"abc" + Null        '  returns Null

// Example in D
"abc" ~ "def";      // returns "abcdef"

;; Example in common lisp
(concatenate 'string "abc " "def " "ghi")  ; returns "abc def ghi"

Contains

Definition	contains(string,substring) returns boolean
Description	Returns whether string contains substring as a substring. This is equivalent to using Find and then detecting that it does not result in the failure condition listed in the third column of the Find section. However, some languages have a simpler way of expressing this test.
Related	Find

Format	Languages
string_in_string(string, loc int, substring)	ALGOL 68
ContainsStr(string, substring)	Object Pascal (Delphi)
strstr(string, substring) != NULL	C, C++ (char * only)
string.Contains(substring)	C#, VB .NET, Windows PowerShell, F#
string.contains(substring)	Cobra, Java (1.5+)
string.indexOf(substring) >= 0	JavaScript
strpos(string, substring) !== false	PHP
pos(string, substring) <> 0	Seed7
substring in string	Cobra, Python (2.3+)
string.find(string, substring) ~= nil	Lua
string.include?(substring)	Ruby
Data.List.isInfixOf substring string	Haskell (GHC 6.6+)
string includesSubstring: substring	Smalltalk (Squeak, Pharo, Smalltalk/X)
String.isSubstring substring string	Standard ML
(search substring string)	Common Lisp
(not (null (string-index substring string)))	ISLISP
(substring? substring string)	Clojure
! StringFreeQ[string, substring]	Mathematica
index(string, substring, startpos)>0	Fortran, PL/I[8]
strings.Contains(string, substring)	Go
string.find(substring) != string::npos	C++
[string containsString:substring]	Objective-C (NSString * only, iOS 8+/OS X 10.10+)
string.rangeOfString(substring) != nil	Swift (Foundation)

¢ Example in ALGOL 68 ¢
string in string("e", loc int, "Hello mate");      ¢ returns true ¢
string in string("z", loc int, "word");            ¢ returns false ¢

// Example In C#
"Hello mate".Contains("e");      // returns true
"word".Contains("z");            // returns false

#  Example in Python
"e" in "Hello mate"              #  returns true
"z" in "word"                    #  returns false

"  Example in Smalltalk "
'Hello mate' includesSubstring: 'e'  " returns true "
'word' includesSubstring: 'z'        " returns false "

Equality

Tests if two strings are equal. See also #Compare and #Compare. Note that doing equality checks via a generic Compare with integer result is not only confusing for the programmer but is often a significantly more expensive operation; this is especially true when using "C-strings".

Format	Languages
string1 == string2	Python, C++ (STL), C#, Cobra, Go, JavaScript (similarity), PHP (similarity), Ruby, Erlang, Haskell, Lua, D, Mathematica, Swift, Ya
string1 === string2	JavaScript, PHP
string1 == string2 or string1 .EQ. string2	Fortran
strcmp(string1, string2) == 0	C
(string=? string1 string2)	Scheme
(string= string1 string2)	Common Lisp, ISLISP
string1 = string2	ALGOL 68, Ada, Object Pascal (Delphi), OCaml, Pascal, Rexx, Seed7, Standard ML, BASIC, VB, VB .NET, F#, Smalltalk, PL/I, COBOL
test string1 = string2, or [ string1 = string2 ]	Bourne Shell
string1 eq string2	Perl
string1.equals(string2)	Cobra, Java
string1.Equals(string2)	C#
string1 -eq string2, or [string]::Equals(string1, string2)	Windows PowerShell
[string1 isEqualToString:string2], or [string1 isEqual:string2]	Objective-C (NSString * only)

// Example in C#
"hello" == "world"           // returns false

' Example in Visual Basic
"hello" = "world"            '  returns false

# Example in Windows PowerShell
"hello" -eq "world"          #  returns false

Find

Definition	find(string,substring) returns integer
Description	Returns the position of the start of the first occurrence of substring in string. If the substring is not found most of these routines return an invalid index value – -1 where indexes are 0-based, 0 where they are 1-based – or some value to be interpreted as Boolean FALSE.
Related	instrrev

Format	Languages	If not found
string in string(substring, pos, string[startpos:])	ALGOL 68	returns BOOL: TRUE or FALSE, and position in REF INT pos.
InStr(«startpos,»string,substring)	VB (positions start at 1)	returns 0
INSTR$(string,substring)	BASIC (positions start at 1)	returns 0
index(string,substring)	AWK	returns 0
index(string,substring«,startpos»)	Perl	returns −1
instr(«startpos,»string,substring)	FreeBASIC	returns 0
strpos(string,substring«,startpos»)	PHP	returns FALSE
locate(string, substring)	Ingres	returns string length + 1
strstr(string, substring)	C, C++ (char * only, returns pointer to first character)	returns NULL
std.string.indexOf(string, substring)	D	returns −1
pos(string, substring«, startpos»)	Seed7	returns 0
strings.Index(string, substring)	Go	returns −1
pos(substring, string)	Pascal, Object Pascal (Delphi)	returns 0
pos(substring, string«,startpos»)	Rexx	returns 0
string.find(substring«,startpos»)	C++ (STL)	returns std::string::npos
string.find(substring«,startpos«,endpos»»)	Python	returns −1
string.index(substring«,startpos«,endpos»»)		raises ValueError
string.index(substring«,startpos»)	Ruby	returns nil
string.indexOf(substring«,startpos»)	Java, JavaScript	returns −1
string.IndexOf(substring«,startpos«, charcount»»)	VB .NET, C#, Windows PowerShell, F#	returns −1
string:str(string, substring)	Erlang	returns 0
(string-contains string substring)	Scheme (SRFI 13)	returns #f
(search substring string)	Common Lisp	returns NIL
(string-index substring string)	ISLISP	returns nil
List.findIndex (List.isPrefixOf substring) (List.tails string)	Haskell (returns Just index)	returns Nothing
Str.search_forward (Str.regexp_string substring) string 0	OCaml	raises Not_found
Substring.size (#1 (Substring.position substring (Substring.full string)))	Standard ML	returns string length
[string rangeOfString:substring].location	Objective-C (NSString * only)	returns NSNotFound
string.find(string, substring) (string):find(substring)	Lua	returns nil
string indexOfSubCollection: substring startingAt: startpos ifAbsent: aBlock string findString: substring startingAt: startpos	Smalltalk (Squeak, Pharo)	evaluate aBlock which is a block closure (or any object understanding value) returns 0
startpos = INDEX(string, substring «,back» «, kind»)	Fortran	returns 0 if substring is not in string; returns LEN(string)+1 if substring is empty
POSITION(substring IN string)	SQL	returns 0 (positions start at 1)
index(string, substring, startpos )	PL/I[8]	returns 0 (positions start at 1)
string.indexOf(substring«,startpos«, charcount»»)	Cobra	returns −1
string first substring string startpos	Tcl	returns −1

; Examples in Common Lisp
(search "e" "Hello mate")             ;  returns 1
(search "z" "word")                   ;  returns NIL

// Examples in C#
"Hello mate".IndexOf("e");            // returns 1
"Hello mate".IndexOf("e", 4);         // returns 9
"word".IndexOf("z");                  // returns -1

; Examples in Scheme
(use-modules (srfi srfi-13))
(string-contains "Hello mate" "e")    ;  returns 1
(string-contains "word" "z")          ;  returns #f

' Examples in Visual Basic
InStr("Hello mate", "e")              '  returns 2
InStr(5, "Hello mate", "e")           '  returns 10
InStr("word", "z")                    '  returns 0

" Examples in Smalltalk "
'Hello mate' indexOfSubCollection:'ate'  "returns 8"
'Hello mate' indexOfSubCollection:'late' "returns 0"
I'Hello mate' 
    indexOfSubCollection:'late'
    ifAbsent:[ 99 ]                      "returns 99"
'Hello mate' 
    indexOfSubCollection:'late'
    ifAbsent:[ self error ]              "raises an exception"

Find character

Definition	find_character(string,char) returns integer
Description	Returns the position of the start of the first occurrence of the character char in string. If the character is not found most of these routines return an invalid index value – -1 where indexes are 0-based, 0 where they are 1-based – or some value to be interpreted as Boolean FALSE. This can be accomplished as a special case of #Find, with a string of one character; but it may be simpler or more efficient in many languages to locate just one character. Also, in many languages, characters and strings are different types, so it is convenient to have such a function.
Related	find

Format	Languages	If not found
char in string(char, pos, string[startpos:])	ALGOL 68	returns BOOL: TRUE or FALSE, and position in REF INT pos.
instr(string, any char«,startpos») (char, can contain more them one char, in which case the position of the first appearance of any of them is returned.)	FreeBASIC	returns 0
strchr(string,char)	C, C++ (char * only, returns pointer to character)	returns NULL
std.string.find(string, dchar)	D	returns −1
string.find(char«,startpos»)	C++ (STL)	returns std::string::npos
pos(string, char«, startpos»)	Seed7	returns 0
strings.IndexRune(string,char)	Go	returns −1
string.indexOf(char«,startpos»)	Java, JavaScript	returns −1
string.IndexOf(char«,startpos«, charcount»»)	VB .NET, C#, Windows PowerShell, F#	returns −1
(position char string)	Common Lisp	returns NIL
(char-index char string)	ISLISP	returns nil
List.elemIndex char string	Haskell (returns Just index)	returns Nothing
String.index string char	OCaml	raises Not_found
position = SCAN (string, set «, back» «, kind») or position = VERIFY (string, set «, back» «, kind»)^[a]	Fortran	returns zero
string indexOf: char ifAbsent: aBlock string indexOf: char string includes: char	Smalltalk	evaluate aBlock which is a BlockClosure (or any object understanding value) returns 0 returns true or false
index(string, char, startpos )	PL/I[9]	returns 0 (positions start at 1)
string.index(?char)	Ruby	returns nil
strpos(string,char,startpos)	PHP	returns false
string.indexOf(char«,startpos«, charcount»»)	Cobra	returns −1

// Examples in C#
"Hello mate".IndexOf('e');              // returns 1
"word".IndexOf('z')                     // returns -1

; Examples in Common Lisp
(position #\e "Hello mate")             ;  returns 1
(position #\z "word")                   ;  returns NIL

^a Given a set of characters, SCAN returns the position of the first character found,^[10] while VERIFY returns the position of the first character that does not belong to the set.^[11]

Format

Definition	format(formatstring, items) returns string
Description	Returns the formatted string representation of one or more items.

Format	Languages	Format string syntax
associate(file, string); putf(file, $formatstring$, items)	ALGOL 68	ALGOL
Format(item, formatstring)	VB
sprintf(formatstring, items)	Perl, PHP, Ruby	C
io_lib:format(formatstring, items)	Erlang
sprintf(outputstring, formatstring, items)	C	C
std.string.format(formatstring, items)	D	C
Format(formatstring, items)	Object Pascal (Delphi)
fmt.Sprintf(formatstring, items)	Go	C
printf -v outputstring formatstring items	Bash shell	C
formatstring % (items)	Python, Ruby	C
formatstring.format(items)	Python	.NET
Printf.sprintf formatstring[12] items	OCaml, F#	C
Text.Printf.printf formatstring items	Haskell (GHC)	C
formatstring printf: items	Smalltalk	C
String.format(formatstring, items)	Java	C
String.Format(formatstring, items)	VB .NET, C#, F#	.NET
(format formatstring items)	Scheme (SRFI 28)	Lisp
(format nil formatstring items)	Common Lisp	Lisp
(format formatstring items)	Clojure	Lisp
formatstring -f items	Windows PowerShell	.NET
[NSString stringWithFormat:formatstring, items]	Objective-C (NSString * only)	C
String(format:formatstring, items)	Swift (Foundation)	C
string.format(formatstring, items) (formatstring):format(items)	Lua	C
WRITE (outputstring, formatstring) items	Fortran	Fortran
put string(string) edit(items)(format)	PL/I	PL/I (similar to Fortran)
String.format(formatstring, items)	Cobra	.NET
format formatstring items	Tcl	C

// Example in C#
String.Format("My {0} costs {1:C2}", "pen", 19.99); // returns "My pen costs $19.99"

// Example in Object Pascal (Delphi)
Format('My %s costs $%2f', ['pen', 19.99]);         // returns "My pen costs $19.99"

// Example in Java
String.format("My %s costs $%2f", "pen", 19.99);    // returns "My pen costs $19.99"

# Example in Python
"My %s costs $%.2f" % ("pen", 19.99);                #  returns "My pen costs $19.99"
"My {0} costs ${1:.2f}".format("pen", 19.99);        #  returns "My pen costs $19.99"

; Example in Scheme
(format "My ~a costs $~1,2F" "pen" 19.99)           ;  returns "My pen costs $19.99"

/* example in PL/I */
put string(some_string) edit('My ', 'pen', ' costs', 19.99)(a,a,a,p'$$$V.99')
/* returns "My pen costs $19.99" */

Inequality

Tests if two strings are not equal. See also #Equality.

Format	Languages
string1 ne string2, or string1 NE string2	ALGOL 68 – note: the operator "ne" is literally in bold type-font.
string1 /= string2	ALGOL 68, Ada, Erlang, Fortran, Haskell
string1 <> string2	BASIC, VB, VB .NET, Pascal, Object Pascal (Delphi), OCaml, PHP, Seed7, Standard ML, F#, COBOL, Cobra, Python 2 (deprecated)
string1 # string2	BASIC (some implementations)
string1 ne string2	Perl
(string<> string1 string2)	Scheme (SRFI 13)
(string/= string1 string2)	Common Lisp
(string/= string1 string2)	ISLISP
(not= string1 string2)	Clojure
string1 != string2	C++ (STL), C#, Go, JavaScript (not similar), PHP (not similar), Python, Ruby, Swift, D, Mathematica
string1 !== string2	JavaScript, PHP
string1 \= string2	Rexx
string1 ¬= string2	PL/I
test string1 != string2, or [ string1 != string2 ]	Bourne Shell
string1 -ne string2, or -not [string]::Equals(string1, string2)	Windows PowerShell
string1 ~= string2	Lua, Smalltalk

// Example in C#
"hello" != "world"    // returns true

' Example in Visual Basic
"hello" <> "world"    '  returns true

;; Example in Clojure
(not= "hello" "world")  ; ⇒ true

# Example in Windows PowerShell
"hello" -ne "world"   #  returns true

index

see #Find

indexof

see #Find

instr

see #Find

instrrev

see #rfind

join

Definition	join(separator, list_of_strings) returns a list of strings joined with a separator
Description	Joins the list of strings into a new string, with the separator string between each of the substrings. Opposite of split.
Related	sprintf

Format	Languages
std.string.join(array_of_strings, separator)	D
string:join(list_of_strings, separator)	Erlang
join(separator, list_of_strings)	Perl, PHP
implode(separator, array_of_strings)	PHP
separator.join(sequence_of_strings)	Python, Swift 1.x
array_of_strings.join(separator)	Ruby, JavaScript
(string-join array_of_strings separator)	Scheme (SRFI 13)
(format nil "~{~a~^separator~}" array_of_strings)	Common Lisp
(clojure.string/join separator list_of_strings) (apply str (interpose separator list_of_strings))	Clojure
strings.Join(array_of_strings, separator)	Go
join(array_of_strings, separator)	Seed7
String.concat separator list_of_strings	OCaml
String.concatWith separator list_of_strings	Standard ML
Data.List.intercalate separator list_of_strings	Haskell (GHC 6.8+)
Join(array_of_strings, separator)	VB
String.Join(separator, array_of_strings)	VB .NET, C#, F#
String.join(separator, array_of_strings)	Java 8+
&{$OFS=$separator; "$array_of_strings"}, or array_of_strings -join separator	Windows PowerShell
[array_of_strings componentsJoinedByString:separator]	Objective-C (NSString * only)
table.concat(table_of_strings, separator)	Lua
{|String streamContents: [ :stream | collectionOfAnything asStringOn: stream delimiter: separator ] collectionOfAnything joinUsing: separator	Smalltalk (Squeak, Pharo)
array_of_strings.join(separator«, final_separator»)	Cobra
sequence_of_strings.joinWithSeparator(separator)	Swift 2.x

// Example in C#
String.Join("-", {"a", "b", "c"})  // "a-b-c"

" Example in Smalltalk "
#('a' 'b' 'c') joinUsing: '-'      " 'a-b-c' "

# Example in Perl
join( '-', ('a', 'b', 'c'));       # 'a-b-c'

# Example in Python
"-".join(["a", "b", "c"])          #  'a-b-c'

# Example in Ruby
["a", "b", "c"].join("-")          #  'a-b-c'

; Example in Scheme
(use-modules (srfi srfi-13))
(string-join '("a" "b" "c") "-")   ;  "a-b-c"

lastindexof

see #rfind

left

Definition	left(string,n) returns string
Description	Returns the left n part of a string. If n is greater than the length of the string then most implementations return the whole string (exceptions exist – see code examples). Note that for variable-length encodings such as UTF-8, UTF-16 or Shift-JIS, it can be necessary to remove string positions at the end, in order to avoid invalid strings.

Format	Languages
string (string'First .. string'First + n - 1)	Ada
substr(string, 0, n)	AWK (changes string), Perl, PHP
LEFT$(string,n)	BASIC, VB
left(string,n)	VB, FreeBASIC, Ingres
strncpy(string2, string, n)	C standard library
string.substr(0,n)	C++ (STL)
[string substringToIndex:n]	Objective-C (NSString * only)
(apply str (take n string))	Clojure
string[0 .. n]	D[13]
string:substr(string, start, length)	Erlang
(subseq string 0 n)	Common Lisp
string[:n]	Cobra, Go, Python
left(string,n «,padchar»)	Rexx, Erlang
string[0, n] string[0..n - 1]	Ruby
string[ .. n]	Seed7
string.Substring(0,n)	VB .NET, C#, Windows PowerShell, F#
leftstr(string, n)	Pascal, Object Pascal (Delphi)
copy (string,1,n)	Turbo Pascal
string.substring(0,n)	Java,[14] JavaScript
(string-take string n)	Scheme (SRFI 13)
take n string	Haskell
String.extract (string, n, NONE)	Standard ML
String.sub string 0 n	OCaml[15]
string.[..n]	F#
string.sub(string, 1, n) (string):sub(1, n)	Lua
string first: n	Smalltalk (Squeak, Pharo)
string(:n)	Fortran
StringTake[string, n]	Mathematica[16]
string («FUNCTION» LENGTH(string) - n:n)	COBOL
string.substring(0, n)	Cobra

/* Examples in Rexx */
left("abcde", 3)         /* returns "abc"      */
left("abcde", 8)         /* returns "abcde   " */
left("abcde", 8, "*")    /* returns "abcde***" */

; Examples in Scheme
(use-modules (srfi srfi-13))
(string-take "abcde", 3) ;  returns "abc" 
(string-take "abcde", 8) ;  error

' Examples in Visual Basic
Left("sandroguidi", 3)   '  returns "san" 
Left("sandroguidi", 100) '  returns "sandroguidi"

// Examples in Ya
"abcde"[0..3] // returns "abc"
"abcde"[0..8] // returns "abcde"

len

see #length

length

Definition	length(string) returns an integer number
Description	Returns the length of a string (not counting the null terminator or any other of the string's internal structural information). An empty string returns a length of 0.

Format	Returns	Languages
string'Length		Ada
UPB string		ALGOL 68
length(string)		Ingres, Perl, Pascal, Object Pascal (Delphi), Rexx, Seed7, SQL, PL/I
len(string)		BASIC, FreeBASIC, Python, Go
length(string), string:len(string)		Erlang
Len(string)		VB
string.Length	Number of 16-bit UTF-16-encoded blocks	VB .NET, C#, Windows PowerShell, F#
string.size OR string.length	Number of bytes[17]	Ruby
strlen(string)	Number of bytes	C, PHP
string.length()		C++ (STL)
string.length		Cobra, D, JavaScript
string.length()	Number of 16-bit UTF-16-encoded blocks	Java
(string-length string)		Scheme
(length string)		Common Lisp, ISLISP
(count string)		Clojure
String.length string		OCaml
size string		Standard ML
length string	Number of Unicode codepoints	Haskell
string.length	Number of 16-bit UTF-16-encoded blocks	Objective-C (NSString * only)
string.characters.count	Number of characters	Swift (2.x)
count(string)	Number of characters	Swift (1.2)
countElements(string)	Number of characters	Swift (1.0–1.1)
string.len(string) (string):len() #string		Lua
string size		Smalltalk
LEN(string), or LEN_TRIM(string)		Fortran
StringLength[string]		Mathematica
Length(string) or Size(string)	number of bytes as $int+	Ya
«FUNCTION» LENGTH(string) or «FUNCTION» BYTE-LENGTH(string)	number of characters and number of bytes, respectively	COBOL
string length string	a decimal string giving the number of characters	Tcl

// Examples in C#
"hello".Length;      // returns 5
"".Length;           // returns 0

# Examples in Erlang
string:len("hello"). %  returns 5
string:len("").      %  returns 0

# Examples in Perl
length("hello");     #  returns 5
length("");          #  returns 0

' Examples in Visual Basic
Len("hello")         '  returns 5
Len("")              '  returns 0

//Examples in Objective-C
[@"hello" Length]   //returns 5
[@"" Length]   //returns 0

-- Examples in Lua
("hello"):len() -- returns 5
#"" -- returns 0

locate

see #Find

Lowercase

Definition	lowercase(string) returns string
Description	Returns the string in lower case.

Format	Languages
LCase(string)	VB
lcase(string)	FreeBASIC
lc(string)	Perl
tolower(char)	C[18]
std.string.toLower(string)	D
transform(string.begin(), string.end(), result.begin(), ::tolower)[19]	C++[20]
lowercase(string)	Object Pascal (Delphi)
strtolower(string)	PHP
lower(string)	Seed7
echo "string" | tr 'A-Z' 'a-z'	Unix
string.lower()	Python
string.downcase	Ruby[21]
strings.ToLower(string)	Go
(string-downcase string)	Scheme (R6RS), Common Lisp
(lower-case string)	Clojure
String.lowercase string	OCaml
String.map Char.toLower string	Standard ML
map Char.toLower string	Haskell
string.toLowerCase()	Java, JavaScript
to_lower(string)	Erlang
string.ToLower()	VB .NET, C#, Windows PowerShell, F#
string.lowercaseString	Objective-C (NSString * only), Swift (Foundation)
string.lower(string) (string):lower()	Lua
string asLowercase	Smalltalk
LOWER(string)	SQL
lowercase(string)	PL/I[5]
ToLowerCase[string]	Mathematica
«FUNCTION» LOWER-CASE(string)	COBOL
string.toLower	Cobra
string tolower string	Tcl

// Example in C#
"Wiki means fast?".ToLower();        // "wiki means fast?"

; Example in Scheme
(use-modules (srfi srfi-13))
(string-downcase "Wiki means fast?") ;  "wiki means fast?"

/* Example in C */
#include <ctype.h>
#include <stdio.h>
int main(void) {
    char string[] = "Wiki means fast?";
    int i;
    for (i = 0; i < sizeof(string) - 1; ++i) {
        /* transform characters in place, one by one */ 
        string[i] = tolower(string[i]);
    }
    puts(string);                       /* "wiki means fast?" */
    return 0;
}

mid

see #substring

partition

Definition	<string>.partition(separator) returns the sub-string before the separator; the separator; then the sub-string after the separator.
Description	Splits the given string by the separator and returns the three substrings that together make the original.

Format	Languages
string.partition(separator)	Python, Ruby(1.9+)
lists:partition(pred, string)	Erlang
split /(separator)/, string, 2	Perl

# Examples in Python
"Spam eggs spam spam and ham".partition('spam')   # ('Spam eggs ', 'spam', ' spam and ham')
"Spam eggs spam spam and ham".partition('X')      # ('Spam eggs spam spam and ham', "", "")

# Examples in Perl
split /(spam)/'Spam eggs spam spam and ham',2;   # ('Spam eggs ', 'spam', ' spam and ham');
split /(X)/'Spam eggs spam spam and ham',2;      # ('Spam eggs spam spam and ham');

replace

Definition	replace(string, find, replace) returns string
Description	Returns a string with find occurrences changed to replace.

Format	Languages
changestr(find, string, replace)	Rexx
std.string.replace(string, find, replace)	D
Replace(string, find, replace)	VB
replace(string, find, replace)	Seed7
string.Replace(find, replace)	VB .NET, C#, F#
str_replace(find, replace, string)	PHP
re:replace(string, find, replace, «{return, list}»)	Erlang
string.replace(find, replace)	Cobra, Python, Java (1.5+)
string.replaceAll(find_regex, replace)[22]	Java
string.gsub(find, replace)	Ruby
string =~ s/find_regex/replace/g[22]	Perl
string.replace(find, replace, "g") [23] or string.replace(/find_regex/g, replace)[22]	JavaScript
echo "string" | sed 's/find_regex/replace/g'[22]	Unix
string.replace(find, replace), or string -replace find_regex, replace[22]	Windows PowerShell
Str.global_replace (Str.regexp_string find) replace string	OCaml
[string stringByReplacingOccurrencesOfString:find withString:replace]	Objective-C (NSString * only)
string.stringByReplacingOccurrencesOfString(find, withString:replace)	Swift (Foundation)
string.gsub(string, find, replace) (string):gsub(find, replace)	Lua
string copyReplaceAll: find with: replace	Smalltalk (Squeak, Pharo)
string map {find replace} string	Tcl
StringReplace[string, find -> replace]	Mathematica
strings.Replace(string, find, replace, -1)	Go
INSPECT string REPLACING ALL/LEADING/FIRST find BY replace	COBOL

// Examples in C#
"effffff".Replace("f", "jump");     // returns "ejumpjumpjumpjumpjumpjump"
"blah".Replace("z", "y");           // returns "blah"

// Examples in Java
"effffff".replace("f", "jump");     // returns "ejumpjumpjumpjumpjumpjump"
"effffff".replaceAll("f*", "jump"); // returns "ejump"

' Examples in Visual Basic
Replace("effffff", "f", "jump")     '  returns "ejumpjumpjumpjumpjumpjump"
Replace("blah", "z", "y")           '  returns "blah"

# Examples in Windows PowerShell
"effffff" -replace "f", "jump"      #  returns "ejumpjumpjumpjumpjumpjump"
"effffff" -replace "f*", "jump"     #  returns "ejump"

reverse

Definition	reverse(string)
Description	Reverses the order of the characters in the string.

Format	Languages
reverse string	Perl, Haskell
lists:reverse(string)	Erlang
strrev(string)	PHP
string[::-1]	Python
(string-reverse string)	Scheme (SRFI 13)
(reverse string)	Common Lisp
string.reverse	Ruby, D (modifies string)
new StringBuilder(string).reverse().toString()	Java
std::reverse(string.begin(), string.end());	C++ (std::string only, modifies string)
StrReverse(string)	VB
string.Reverse().ToString()	VB .NET, C#
implode (rev (explode string))	Standard ML
string.split("").reverse().join("")	JavaScript
string.reverse(string) (string):reverse()	Lua
string reverse	Smalltalk
StringReverse[string]	Mathematica
reverse(string)	PL/I
«FUNCTION» REVERSE(string)	COBOL
string.toCharArray.toList.reversed.join()	Cobra
String(string.characters.reverse())	Swift (2.x)
String(reverse(string))	Swift (1.2)
string reverse string	Tcl

" Example in Smalltalk "
'hello' reversed             " returns 'olleh' "

# Example in Perl
reverse "hello"              # returns "olleh"

# Example in Python
"hello"[::-1]                # returns "olleh"

; Example in Scheme
(use-modules (srfi srfi-13))
(string-reverse "hello")     ; returns "olleh"

rfind

Definition	rfind(string,substring) returns integer
Description	Returns the position of the start of the last occurrence of substring in string. If the substring is not found most of these routines return an invalid index value – -1 where indexes are 0-based, 0 where they are 1-based – or some value to be interpreted as Boolean FALSE.
Related	instr

Format	Languages	If not found
InStrRev(«startpos,» string,substring)	VB	returns 0
instrrev(«startpos,» string,substring)	FreeBASIC	returns 0
rindex(string,substring«,startpos»)	Perl	returns −1
strrpos(string,substring«,startpos»)	PHP	returns FALSE
string.rfind(substring«,startpos»)	C++ (STL)	returns std::string::npos
std.string.rfind(string, substring)	D	returns −1
string.rfind(substring«,startpos«, endpos»»)	Python	returns −1
string.rindex(substring«,startpos«, endpos»»)		raises ValueError
rpos(string, substring«,startpos»)	Seed7	returns 0
string.rindex(substring«,startpos»)	Ruby	returns nil
strings.LastIndex(string, substring)	Go	returns −1
string.lastIndexOf(substring«,startpos»)	Java, JavaScript	returns −1
string.LastIndexOf(substring«,startpos«, charcount»»)	VB .NET, C#, Windows PowerShell, F#	returns −1
(search substring string :from-end t)	Common Lisp	returns NIL
[string rangeOfString:substring options:NSBackwardsSearch].location	Objective-C (NSString * only)	returns NSNotFound
Str.search_backward (Str.regexp_string substring) string (Str.length string - 1)	OCaml	raises Not_found
string.match(string, '.*()'..substring) string:match('.*()'..substring)	Lua	returns nil
Ada.Strings.Unbounded.Index(Source => string, Pattern => substring, Going => Ada.Strings.Backward)	Ada	returns 0
string.lastIndexOf(substring«,startpos«, charcount»»)	Cobra	returns −1
string lastIndexOfString:substring	Smalltalk	returns 0
string last substring string startpos	Tcl	returns −1

; Examples in Common Lisp
(search "e" "Hello mate" :from-end t)     ;  returns 9
(search "z" "word" :from-end t)           ;  returns NIL

// Examples in C#
"Hello mate".LastIndexOf("e");           // returns 9
"Hello mate".LastIndexOf("e", 4);        // returns 1
"word".LastIndexOf("z");                 // returns -1

' Examples in Visual Basic
InStrRev("Hello mate", "e")              '  returns 10
InStrRev(5, "Hello mate", "e")           '  returns 2
InStrRev("word", "z")                    '  returns 0

right

Definition	right(string,n) returns string
Description	Returns the right n part of a string. If n is greater than the length of the string then most implementations return the whole string (exceptions exist – see code examples).

Format	Languages
string (string'Last - n + 1 .. string'Last)	Ada
Right(string,n)	VB
RIGHT$(string,n)	BASIC
right(string,n)	FreeBASIC, Ingres
strcpy(string2, string+n) (n must not be greater than the length of string)	C
string.Substring(string.Length()-n)	C#
string.substring(string.length()-n)	Java
string.slice(-n)	JavaScript[24]
right(string,n «,padchar»)	Rexx, Erlang
substr(string,-n)	Perl, PHP
string[-n:]	Cobra, Python
(string-take-right string n)	Scheme (SRFI 13)
string[-n..-1]	Ruby, Ya
string[$-n .. $]	D[25]
String.sub string (String.length string - n) n	OCaml[15]
string.sub(string, -n) (string):sub(-n)	Lua
string last: n	Smalltalk (Squeak, Pharo)
StringTake[string, -n]	Mathematica[16]
string (1:n)	COBOL

/* Examples in Rexx */
right("abcde", 3)              /* returns "cde"      */
right("abcde", 8)              /* returns "   abcde" */
right("abcde", 8, "*")         /* returns "***abcde" */

; Examples in Scheme
(use-modules (srfi srfi-13))
(string-take-right "abcde", 3) ;  returns "cde" 
(string-take-right "abcde", 8) ;  error

' Examples in Visual Basic
Right("sandroguidi", 3)        '  returns "idi" 
Right("sandroguidi", 100)      '  returns "sandroguidi"

// Examples in Java; extract rightmost 4 characters
String str = "CarDoor";
str.substring(str.length()-4); // returns 'Door'

rpartition

Definition	<string>.rpartition(separator) Searches for the separator from right-to-left within the string then returns the sub-string before the separator; the separator; then the sub-string after the separator.
Description	Splits the given string by the right-most separator and returns the three substrings that together make the original.

Format	Languages
string.rpartition(separator)	Python, Ruby

# Examples in Python
"Spam eggs spam spam and ham".rpartition('spam')  ### ('Spam eggs spam ', 'spam', ' and ham')
"Spam eggs spam spam and ham".rpartition('X')     ### ("", "", 'Spam eggs spam spam and ham')

slice

see #substring

split

Definition

<string>.split(separator[, limit]) splits a string on separator, optionally only up to a limited number of substrings

Description

Splits the given string by occurrences of the separator (itself a string) and returns a list (or array) of the substrings. If limit is given, after limit – 1 separators have been read, the rest of the string is made into the last substring, regardless of whether it has any separators in it. The Scheme and Erlang implementations are similar but differ in several ways. JavaScript differs also in that it cuts, it does not put the rest of the string into the last element. See the example here. The Cobra implementation will default to whitespace. Opposite of join.

Format	Languages
split(/separator/, string«, limit»)	Perl
explode(separator, string«, limit»)	PHP
string.split(separator«, limit-1»)	Python
string.split(separator«, limit»)	JavaScript, Java, Ruby
string:tokens(string, sepchars)	Erlang
strings.Split(string, separator) strings.SplitN(string, separator, limit)	Go
(string-tokenize string« charset« start« end»»»)	Scheme (SRFI 13)
Split(string, sepchars«, limit»)	VB
string.Split(sepchars«, limit«, options»»)	VB .NET, C#, F#
string -split separator«, limit«, options»»	Windows PowerShell
Str.split (Str.regexp_string separator) string	OCaml
std.string.split(string, separator)	D
[string componentsSeparatedByString:separator]	Objective-C (NSString * only)
string.componentsSeparatedByString(separator)	Swift (Foundation)
TStringList.Delimiter, TStringList.DelimitedText	Object Pascal
StringSplit[string, separator«, limit»]	Mathematica
string.split«(sepchars«, limit«, options»»)»	Cobra
split string separator	Tcl

// Example in C#
"abc,defgh,ijk".Split(',');                 // {"abc", "defgh", "ijk"}
"abc,defgh;ijk".Split(',', ';');            // {"abc", "defgh", "ijk"}

% Example in Erlang
string:tokens("abc;defgh;ijk", ";").        %  ["abc", "defgh", "ijk"]

// Examples in Java
"abc,defgh,ijk".split(",");                 // {"abc", "defgh", "ijk"}
"abc,defgh;ijk".split(",|;");               // {"abc", "defgh", "ijk"}

{ Example in Pascal }
var
  lStrings: TStringList;
  lStr: string;
begin
  lStrings := TStringList.Create;
  lStrings.Delimiter := ',';
  lStrings.DelimitedText := 'abc,defgh,ijk';
  lStr := lStrings.Strings[0]; // 'abc'
  lStr := lStrings.Strings[1]; // 'defgh'
  lStr := lStrings.Strings[2]; // 'ijk'
end;

# Examples in Perl
split(/spam/, 'Spam eggs spam spam and ham'); # ('Spam eggs ', ' ', ' and ham')
split(/X/, 'Spam eggs spam spam and ham');    #  ('Spam eggs spam spam and ham')

sprintf

see #Format

strip

see #trim

strcmp

see #Compare (integer result)

substring

Definition

substring(string, startpos, endpos) returns string substr(string, startpos, numChars) returns string

Description

Returns a substring of string between starting at startpos and endpos, or starting at startpos of length numChars. The resulting string is truncated if there are fewer than numChars characters beyond the starting point. endpos represents the index after the last character in the substring. Note that for variable-length encodings such as UTF-8, UTF-16 or Shift-JIS, it can be necessary to remove string positions at the end, in order to avoid invalid strings.

Format	Languages
string[startpos:endpos]	ALGOL 68 (changes base index)
string (startpos .. endpos)	Ada (changes base index)
Mid(string, startpos, numChars)	VB
mid(string, startpos, numChars)	FreeBASIC
MID$(string, startpos, numChars)	BASIC
substr(string, startpos, numChars)	AWK (changes string), Perl,[26][27] PHP[26][27]
substr(string, startpos «,numChars, padChar»)	Rexx
string[startpos:endpos]	Cobra, Python,[26][28] Go
string[startpos, numChars] string[startpos .. endpos-1] string[startpos ... endpos]	Ruby[26][28]
string[startpos .. endpos] string[startpos len numChars]	Seed7
string.slice(startpos«, endpos»)	JavaScript[26][28]
string.substr(startpos«, numChars»)	C++ (STL), JavaScript
string.Substring(startpos, numChars)	VB .NET, C#, Windows PowerShell, F#
string.substring(startpos«, endpos»)	Java, JavaScript
copy(string, startpos, numChars)	Object Pascal (Delphi)
(substring string startpos endpos)	Scheme
(subseq string startpos endpos)	Common Lisp
(subseq string startpos endpos)	ISLISP
String.sub string startpos numChars	OCaml
substring (string, startpos, numChars)	Standard ML
string:sub_string(string, startpos, endpos) string:substr(string, startpos, numChars)	Erlang
strncpy(result, string + startpos, numChars);	C
string[startpos .. endpos+1]	D
take numChars $ drop startpos string	Haskell
[string substringWithRange:NSMakeRange(startpos, numChars)]	Objective-C (NSString * only)
string.[startpos..endpos]	F#
string.sub(string, startpos, endpos) (string):sub(startpos, endpos)	Lua[26][28]
string copyFrom: startpos to: endpos	Smalltalk
string(startpos:endpos)	Fortran
SUBSTRING(string FROM startpos «FOR numChars»)	SQL
StringTake[string, {startpos, endpos}]	Mathematica[26][28]
string[startpos .. endpos]	Ya	string (startpos:numChars)
string range string startpos endpos	Tcl

// Examples in C#
"abc".Substring(1, 1):      // returns "b"
"abc".Substring(1, 2);      // returns "bc"
"abc".Substring(1, 6);      // error

;; Examples in Common Lisp
(subseq "abc" 1 2)          ; returns "b"
(subseq "abc" 2)            ; returns "c"

% Examples in Erlang
string:substr("abc", 2, 1). %  returns "b"
string:substr("abc", 2).    %  returns "bc"

# Examples in Python
"abc"[1:2]                 #  returns "b"
"abc"[1:3]                 #  returns "bc"

/* Examples in Rexx */
substr("abc", 2, 1)         /* returns "b"      */
substr("abc", 2)            /* returns "bc"     */
substr("abc", 2, 6)         /* returns "bc    " */
substr("abc", 2, 6, "*")    /* returns "bc****" */

Uppercase

Definition	uppercase(string) returns string
Description	Returns the string in upper case.

Format	Languages
UCase(string)	VB
ucase(string)	FreeBASIC
toupper(string)	AWK (changes string)
uc(string)	Perl
toupper(char)	C (operates on one character)
for(size_t i = 0, len = strlen(string); i< len; i++) string[i] = toupper(string[i]); for (char *c = string; *c != '\0'; c++) *c = toupper(*c);	C (string / char array)
std.string.toUpper(string)	D
transform(string.begin(), string.end(), result.begin(), toupper)[19]	C++[29]
uppercase(string)	Object Pascal (Delphi)
upcase(char)	Object Pascal (Delphi) (operates on one character)
strtoupper(string)	PHP
upper(string)	Seed7
echo "string" | tr 'a-z' 'A-Z'	Unix
translate(string), or UPPER variables, or PARSE UPPER VAR SrcVar DstVar	Rexx
string.upper()	Python
string.upcase	Ruby [21]
strings.ToUpper(string)	Go
(string-upcase string)	Scheme, Common Lisp
String.uppercase string	OCaml
String.map Char.toUpper string	Standard ML
map Char.toUpper string	Haskell
string.toUpperCase()	Java, JavaScript
to_upper(string)	Erlang
string.ToUpper()	VB .NET, C#, Windows PowerShell, F#
string.uppercaseString	Objective-C (NSString * only), Swift (Foundation)
string.upper(string) (string):upper()	Lua
string asUppercase	Smalltalk
UPPER(string)	SQL
ToUpperCase[string]	Mathematica
«FUNCTION» UPPER-CASE(string)	COBOL
string.toUpper	Cobra
string toupper string	Tcl

// Example in C#
"Wiki means fast?".ToUpper();      // "WIKI MEANS FAST?"

/* Example in Rexx */
translate("Wiki means fast?")      /* "WIKI MEANS FAST?" */

/* Example #2 */
A='This is an example.'
UPPER A                            /* "THIS IS AN EXAMPLE." */

/* Example #3 */
A='upper using Translate Function.'
Translate UPPER VAR A Z            /* Z="UPPER USING TRANSLATE FUNCTION." */

; Example in Scheme
(use-modules (srfi srfi-13))
(string-upcase "Wiki means fast?") ;  "WIKI MEANS FAST?"

' Example in Visual Basic
UCase("Wiki means fast?")          '  "WIKI MEANS FAST?"

trim

trim or strip is used to remove whitespace from the beginning, end, or both beginning and end, of a string.

Example usage	Languages
String.Trim([chars])	C#, VB.NET, Windows PowerShell
string.strip();	D
(.trim string)	Clojure
sequence [ predicate? ] trim	Factor
(string-trim '(#\Space #\Tab #\Newline) string)	Common Lisp
(string-trim string)	Scheme
string.trim()	Java, JavaScript (1.8.1+, Firefox 3.5+)
Trim(String)	Pascal,[30] QBasic, Visual Basic, Delphi
string.strip()	Python
strings.Trim(string, chars)	Go
LTRIM(RTRIM(String))	Oracle SQL, T-SQL
strip(string [,option, char])	REXX
string:strip(string [,option, char])	Erlang
string.strip or string.lstrip or string.rstrip	Ruby
string =~ s/^\s+//r =~ s/\s+$//r	Perl 5
string.trim	Perl 6
trim(string)	PHP
[string stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]]	Objective-C using Cocoa
string withBlanksTrimmed string withoutSpaces string withoutSeparators	Smalltalk (Squeak, Pharo) Smalltalk
strip(string)	SAS
string trim $string	Tcl
TRIM(string) or TRIM(ADJUSTL(string))	Fortran
TRIM(string)	SQL
TRIM(string) or LTrim(string) or RTrim(String)	ColdFusion
String.trim string	OCaml 4+

Other languages

In languages without a built-in trim function, it is usually simple to create a custom function which accomplishes the same task.

AWK

In AWK, one can use regular expressions to trim:

 ltrim(v) = gsub(/^[ \t]+/, "", v)
 rtrim(v) = gsub(/[ \t]+$/, "", v)
 trim(v)  = ltrim(v); rtrim(v)

or:

 function ltrim(s) { sub(/^[ \t]+/, "", s); return s }
 function rtrim(s) { sub(/[ \t]+$/, "", s); return s }
 function trim(s)  { return rtrim(ltrim(s)); }

C/C++

There is no standard trim function in C or C++. Most of the available string libraries^[31] for C contain code which implements trimming, or functions that significantly ease an efficient implementation. The function has also often been called EatWhitespace in some non-standard C libraries.

In C, programmers often combine a ltrim and rtrim to implement trim:

#include <string.h>
#include <ctype.h>

void rtrim(char *str)
{
  char *s;
  s = str + strlen(str);
  while (--s >= str) {
    if (!isspace(*s)) break;
    *s = 0;
  }
}

void ltrim(char *str)
{
  size_t n;
  n = 0;
  while (str[n] != '\0' && isspace((unsigned char)str[n])) {
    n++;
  }
  memmove(str, str + n, strlen(str) - n + 1);
}

void trim(char *str)
{
  rtrim(str);
  ltrim(str);
}

The open source C++ library Boost has several trim variants, including a standard one:^[32]

#include <boost/algorithm/string/trim.hpp>
trimmed = boost::algorithm::trim_copy("string");

Note that with boost's function named simply trim the input sequence is modified in-place, and does not return a result.

Another open source C++ library Qt has several trim variants, including a standard one:^[33]

#include <QString>
trimmed = s.trimmed();

The Linux kernel also includes a strip function, strstrip(), since 2.6.18-rc1, which trims the string "in place". Since 2.6.33-rc1, the kernel uses strim() instead of strstrip() to avoid false warnings.^[34]

Haskell

A trim algorithm in Haskell:

 import Data.Char (isSpace)
 trim      :: String -> String
 trim      = f . f
    where f = reverse . dropWhile isSpace

may be interpreted as follows: f drops the preceding whitespace, and reverses the string. f is then again applied to its own output. Note that the type signature (the second line) is optional.

J

The trim algorithm in J is a functional description:

     trim =. #~ [: (+./\ *. +./\.) ' '&~:

That is: filter (#~) for non-space characters (' '&~:) between leading (+./\) and (*.) trailing (+./\.) spaces.

JavaScript

There is a built-in trim function in JavaScript 1.8.1 (Firefox 3.5 and later), and the ECMAScript 5 standard. In earlier versions it can be added to the String object's prototype as follows:

String.prototype.trim = function() {
  return this.replace(/^\s+/g, "").replace(/\s+$/g, "");
};

Perl

Perl 5 has no built-in trim function. However, the functionality is commonly achieved using regular expressions.

Example:

$string =~ s/^\s+//;            # remove leading whitespace
$string =~ s/\s+$//;            # remove trailing whitespace

or:

$string =~ s/^\s+|\s+$//g ;     # remove both leading and trailing whitespace

These examples modify the value of the original variable $string.

Also available for Perl is StripLTSpace in String::Strip from CPAN.

There are, however, two functions that are commonly used to strip whitespace from the end of strings, chomp and chop:

• chop removes the last character from a string and returns it.
• chomp removes the trailing newline character(s) from a string if present. (What constitutes a newline is $INPUT_RECORD_SEPARATOR dependent).

In Perl 6, the upcoming major revision of the language, strings have a trim method.

Example:

$string = $string.trim;     # remove leading and trailing whitespace
$string .= trim;            # same thing

Tcl

The Tcl string command has three relevant subcommands: trim, trimright and trimleft. For each of those commands, an additional argument may be specified: a string that represents a set of characters to remove—the default is whitespace (space, tab, newline, carriage return).

Example of trimming vowels:

set string onomatopoeia
set trimmed [string trim $string aeiou]         ;# result is nomatop
set r_trimmed [string trimright $string aeiou]  ;# result is onomatop
set l_trimmed [string trimleft $string aeiou]   ;# result is nomatopoeia

XSLT

XSLT includes the function normalize-space(string) which strips leading and trailing whitespace, in addition to replacing any whitespace sequence (including line breaks) with a single space.

Example:

<xsl:variable name='trimmed'>
   <xsl:value-of select='normalize-space(string)'/>
</xsl:variable>

XSLT 2.0 includes regular expressions, providing another mechanism to perform string trimming.

Another XSLT technique for trimming is to utilize the XPath 2.0 substring() function.

References

1. the index can be negative, which then indicates the number of places before the end of the string.
2. returns LESS, EQUAL, or GREATER
3. returns LT, EQ, or GT
4. returns .TRUE. or .FALSE.. These functions are based on the ASCII collating sequence.
5. IBM extension.
6. The operators use the compiler's default collating sequence.
7. modifies string1, which must have enough space to store the result
8. startpos is IBM extension.
9. startpos is IBM extension.
10. "scan in Fortran Wiki". Fortranwiki.org. 2009-04-30. Retrieved 2013-08-18.
11. "verify in Fortran Wiki". Fortranwiki.org. 2012-05-03. Retrieved 2013-08-18.
12. formatstring must be a fixed literal at compile time for it to have the correct type.
13. if n is larger than the length of the string, then in Debug mode ArrayRangeException is thrown, in Release mode, the behaviour is unspecified.
14. if n is larger than the length of the string, Java will throw an IndexOutOfBoundsException
15. if n is larger than length of string, raises Invalid_argument
16. if n is larger than length of string, throw the message "StringTake::take:"
17. Ruby lacks Unicode support
18. operates on one character
19. The transform function exists in the std:: namespace. You must include the <algorithm> header file to use it. The tolower and toupper functions are in the global namespace, obtained by the <ctype.h> header file. The std::tolower and std::toupper names are overloaded and cannot be passed to std::transform without a cast to resolve a function overloading ambiguity, e.g. std::transform(string.begin(), string.end(), result.begin(), (int (*)(int))std::tolower);
20. std::string only, result is stored in string result which is at least as long as string, and may or may not be string itself
21. only ASCII characters as Ruby lacks Unicode support
22. The "find" string in this construct is interpreted as a regular expression. Certain characters have special meaning in regular expressions. If you want to find a string literally, you need to quote the special characters.
23. third parameter is non-standard
24. "Annotated ES5". Es5.github.com. Retrieved 2013-08-18.
25. if n is larger than length of string, then in Debug mode ArrayRangeException is thrown, and unspecified behaviour in Release mode
26. startpos can be negative, which indicates to start that number of places before the end of the string.
27. numChars can be negative, which indicates to end that number of places before the end of the string.
28. endpos can be negative, which indicates to end that number of places before the end of the string.
29. std::string only, result is stored in string result which is at least as long as string, and may or may not be string itself
30. "Trim – GNU Pascal priručnik". Gnu-pascal.de. Retrieved 2013-08-24.
31. "String library comparison". And.org. Retrieved 2013-08-24.
32. "Usage – 1.54.0". Boost.org. 2013-05-22. Retrieved 2013-08-24.
33. Archived August 2, 2009, at the Wayback Machine.
34. dankamongmen. "sprezzos-kernel-packaging/changelog at master · dankamongmen/sprezzos-kernel-packaging · GitHub". Github.com. Retrieved 2016-05-29.

External links

• Perl String Functions
• Python 2 String Methods
• Python 3 String Methods
• Scheme String Procedures
• Erlang String Functions
• .NET String Methods and Properties
• Ruby String Class
• PHP String functions
• java.lang.String members
• Haskell Hierarchical Libraries
• Arrays in D (in D strings are regular arrays)
• std.string from Phobos (D standard library)
• Lua String Functions
• OCaml String module
• Common Lisp String manipulation
• FreeBASIC String Functions
• Reference.wolfram.com
• Tcl reference for string commands