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.
FormatLanguagesBase index
string[i] ALGOL 68, APL, Julia, Pascal, Object Pascal (Delphi), Seed7 1
string[i] C, C++, C#, Cobra, D, FreeBASIC, Go, Python,[1] PHP, Ruby,[1] Windows PowerShell, JavaScript, APL 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.chars().nth(i) Rust[2] 0
string[i,1] Pick Basic 1
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 5[1] 0
substr(string, i, 1)
string.substr(i, 1)		 Raku[3] 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
${string_param:i:1} Bash 0
i⌷string APL 0 or 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
#include <stdio.h>             // for printf
char MyStr[] = "Hello, World";
printf("%c", *(MyStr+1));      // 'e'
printf("%c", *(MyStr+7));      // 'W'
printf("%c", MyStr[11]);       // 'd'
printf("%s", MyStr);           // 'Hello, World'
printf("%s", "Hello(2), World(2)"); // 'Hello(2), World(2)'

// Example in C++
#include <iostream>            // for "cout"
#include <string.h>            // for "string" data type
using namespace std;
char MyStr1[] = "Hello(1), World(1)";
string MyStr2 = "Hello(2), World(2)";
cout << "Hello(3), World(3)";  // 'Hello(3), World(3)'
cout << MyStr2[6];             // '2'
cout << MyStr1.substr (5, 3);  // '(1)'

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

# Example in Perl 5
substr("Hello, World", 1, 1);  # 'e'

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

# Example in Raku
"Hello, World".substr(1, 1);   # 'e'

' 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"

//Example in Rust
"Hello, World".chars().nth(2);   // Some('l')

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.
FormatLanguages
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, Raku
string1 compare: string2 Smalltalk (Squeak, Pharo)
string1 <=> string2 Ruby, C++ (STL, C++20)[4]
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[5]
compare string1 string2 Haskell[6]
[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[7]
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[8]
string1.cmp(string2) Rust[9]
# Example in Perl 5
"hello" cmp "world";       # returns -1

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

# Examples in Raku
"hello" cmp "world";       # returns Less
"world" cmp "hello";       # returns More
"hello" cmp "hello";       # returns Same

/** 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.
FormatLanguages
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, Raku
string1 OP string2, where OP can be any of ==, !=, <, >, <= and >= C++ (STL), C#, D, Go, JavaScript, Python, PHP, Ruby, Rust,[10] Swift
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.[11]
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
string1.METHOD(string2) where METHOD is any of eq, ne, gt, lt, ge, le Rust[10]
% Example in Erlang
"hello" > "world".            % returns false

# Example in Raku
"art" gt "painting";           # returns False
"art" lt "painting";           # returns True

# 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.
FormatLanguages
string1 & string2 Ada, FreeBASIC, Seed7, BASIC, VB, VB .NET, COBOL (between literals only)
strcat(string1, string2) C, C++ (char * only)[12]
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,[13] F#, Swift, Turing, VB
string1 ~ string2 D, Raku
(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, APL
string1 string2 SNOBOL
string1string2 Bash
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"

# Example in Perl 5
"abc" . "def";      # returns "abcdef"
"Perl " . 5;        # returns "Perl 5"

# Example in Raku
"abc" ~ "def";      # returns "abcdef"
"Perl " ~ 6;        # returns "Perl 6"

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
FormatLanguages
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+), Raku, Rust,[14] C++ (C++23)[15]
string.indexOf(substring) >= 0 JavaScript
strpos(string, substring) !== false PHP
str_contains(string, substring) PHP (8+)
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[16]
index(string, substring, occurrence)>0 Pick Basic
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)
∨/substring⍷string APL
¢ 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 Raku
"Good morning!".contains('z')    #  returns False
"¡Buenos días!".contains('í');   #  returns True

"  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".

FormatLanguages
string1 == string2 Python, C++ (STL), C#, Cobra, Go, JavaScript (similarity), PHP (similarity), Ruby, Rust,[10] Erlang, Haskell, Lua, D, Mathematica, Swift
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, Raku
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)
string1 ≡ string2 APL
string1.eq(string2) Rust[10]
// Example in C#
"hello" == "world"           // returns false

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

# Examples in Perl 5
'hello' eq 'world'           # returns 0
'hello' eq 'hello'           # returns 1

# Examples in Raku
'hello' eq 'world'           # returns False
'hello' eq 'hello'           # returns True

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

⍝ Example in APL
'hello' ≡ 'world'          ⍝  returns 0


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
FormatLanguagesIf 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 5 returns −1
index(string,substring«,startpos»)
string.index(substring,«,startpos»)		 Raku returns Nil
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 only 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[16] returns 0 (positions start at 1)
index(string, substring, occurrence ) Pick Basic returns 0 if occurrence of substring is not in string; (positions start at 1)
string.indexOf(substring«,startpos«, charcount»») Cobra returns −1
string first substring string startpos Tcl returns −1
(substring⍷string)⍳1 APL returns 1 + the last position in string
string.find(substring) Rust[17] returns None

Examples

  • Common Lisp 
    (search "e" "Hello mate")             ;  returns 1
(search "z" "word")                   ;  returns NIL
  • C# 
    "Hello mate".IndexOf("e");            // returns 1
"Hello mate".IndexOf("e", 4);         // returns 9
"word".IndexOf("z");                  // returns -1
  • Raku 
    "Hello, there!".index('e')           # returns 1
"Hello, there!".index('z')           # returns Nil
  • Scheme 
    (use-modules (srfi srfi-13))
(string-contains "Hello mate" "e")    ;  returns 1
(string-contains "word" "z")          ;  returns #f
  • Visual Basic 
    ' Examples in 
InStr("Hello mate", "e")              '  returns 2
InStr(5, "Hello mate", "e")           '  returns 10
InStr("word", "z")                    '  returns 0
  • 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
FormatLanguagesIf 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[18] 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
string⍳char APL returns 1 + the last position in string
string.find(substring) Rust[17] returns None
// 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,[19] while VERIFY returns the position of the first character that does not belong to the set.[20]

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, Raku, Ruby C
item.fmt(formatstring) Raku C
io_lib:format(formatstring, items) Erlang
sprintf(outputstring, formatstring, items) C C
std::format(formatstring, items) C++ (C++20) Python
std.string.format(formatstring, items) D C
Format(formatstring, items) Object Pascal (Delphi)
fmt.Sprintf(formatstring, items) Go C
printf formatstring items Unix C
formatstring % (items) Python, Ruby C
formatstring.format(items) Python .NET
fformatstring Python 3
Printf.sprintf formatstring[21] 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
formatnumbers ⍕ items or formatstring ⎕FMT items APL APL
format!(formatstring, items) Rust[22] Python
// 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"

# Examples in Raku
sprintf "My %s costs \$%.2f", "pen", 19.99;          # returns "My pen costs $19.99"
1.fmt("%04d");                                       # returns "0001"

# 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 Python 3.6+
pen = "pen"
f"My {pen} costs {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.

FormatLanguages
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, Raku
(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, Rust,[10] 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
string1 ≢ string2 APL
string1.ne(string2) Rust[10]
// Example in C#
"hello" != "world"    // returns true

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

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

# Example in Perl 5
'hello' ne 'world'      # returns 1

# Example in Raku
'hello' ne 'world'      # returns 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
FormatLanguages
std.string.join(array_of_strings, separator) D
string:join(list_of_strings, separator) Erlang
join(separator, list_of_strings) Perl, PHP, Raku
implode(separator, array_of_strings) PHP
separator.join(sequence_of_strings) Python, Swift 1.x
array_of_strings.join(separator) Ruby, JavaScript, Raku, Rust[23]
(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
1↓∊separator,¨list_of_strings APL
// Example in C#
String.Join("-", {"a", "b", "c"})  // "a-b-c"

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

# Example in Perl 5
join( '-', ('a', 'b', 'c'));       # 'a-b-c'

# Example in Raku
<a b c>.join('-');       # '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.
FormatLanguages
string (string'First .. string'First + n - 1) Ada
substr(string, 0, n) AWK (changes string), Perl, PHP, Raku
LEFT$(string,n) BASIC, VB
left(string,n) VB, FreeBASIC, Ingres, Pick Basic
strncpy(string2, string, n) C standard library
string.substr(0,n) C++ (STL), Raku
[string substringToIndex:n] Objective-C (NSString * only)
(apply str (take n string)) Clojure
string[0 .. n] D[24]
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[1, n] Pick Basic
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,[25] 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[26]
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[27]
string («FUNCTION» LENGTH(string) - n:n) COBOL
string.substring(0, n) Cobra
n↑string. APL
string[0..n]
string[..n]
string.get(0..n)
string.get(..n)		 Rust[28]
# Example in Raku
"Hello, there!".substr(0, 6);  # returns "Hello,"

/* 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"


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.
FormatReturnsLanguages
string'Length Ada
UPB string ALGOL 68
echo "${#string_param}" Bash
length(string) Ingres, Perl 5, Pascal, Object Pascal (Delphi), Rexx, Seed7, SQL, PL/I
len(string) BASIC, FreeBASIC, Python, Go, Pick Basic
length(string), string:len(string) Erlang
Len(string) VB, Pick Basic
string.Length Number of UTF-16 code units VB .NET, C#, Windows PowerShell, F#
chars(string)
string.chars		 Number of graphemes (NFG) Raku
codes(string)
string.codes		 Number of Unicode code points Raku
string.size OR string.length Number of bytes[29] Ruby
strlen(string) Number of bytes C, PHP
string.length() C++ (STL)
string.length Cobra, D, JavaScript
string.length() Number of UTF-16 code units 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 code points Haskell
string.length Number of UTF-16 code units 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
«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
≢ string APL
string.len() Number of bytes Rust[30]
string.chars().count() Number of Unicode code points Rust[31]
// 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 5
length("hello");     #  returns 5
length("");          #  returns 0

# Examples in Raku
"🏳️‍🌈".chars; chars "🏳️‍🌈";      # both return 1
"🏳️‍🌈".codes; codes "🏳️‍🌈";      # both return 4
"".chars; chars "";          # both return 0
"".codes; codes "";          # both return 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.
FormatLanguages
LCase(string) VB
lcase(string) FreeBASIC
lc(string) Perl, Raku
string.lc Raku
tolower(char) C[32]
std.string.toLower(string) D
transform(string.begin(), string.end(), result.begin(), ::tolower)[33] C++[34]
lowercase(string) Object Pascal (Delphi)
strtolower(string) PHP
lower(string) Seed7
${string_param,,} Bash
echo "string" | tr 'A-Z' 'a-z' Unix
string.lower() Python
downcase(string) Pick Basic
string.downcase Ruby[35]
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[8]
ToLowerCase[string] Mathematica
«FUNCTION» LOWER-CASE(string) COBOL
string.toLower Cobra
string tolower string Tcl
string.to_lowercase() Rust[36]
// 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;
}

# Example in Raku
"Wiki means fast?".lc;             # "wiki means fast?"


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.
FormatLanguagesComments
string.partition(separator) Python, Ruby(1.9+)
lists:partition(pred, string) Erlang
split /(separator)/, string, 2 Perl 5
split separator, string, 2
string.split( separator, 2 )		 Raku Separator does not have to be a regular expression
# 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 5 / Raku
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.
FormatLanguages
changestr(find, string, replace) Rexx
std.string.replace(string, find, replace) D
Replace(string, find, replace) VB
replace(string, find, replace) Seed7
change(string, find, replace) Pick Basic
string.Replace(find, replace) C#, F#, VB .NET
str_replace(find, replace, string) PHP
re:replace(string, find, replace, «{return, list}») Erlang
string.replace(find, replace) Cobra, Java (1.5+), Python, Rust[37]
string.replaceAll(find_regex, replace)[38] Java
string.gsub(find, replace) Ruby
string =~ s/find_regex/replace/g[38] Perl 5
string.subst(find, replace, :g) Raku
string.replace(find, replace, "g") [39] or
string.replace(/find_regex/g, replace)[38]		 JavaScript
echo "string" | sed 's/find_regex/replace/g'[38] Unix
${string_param//find_pattern/replace} Bash
string.replace(find, replace), or
string -replace find_regex, replace[38]		 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
find_regex ⎕R replace_regex ⊢ string APL
// 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 Raku
"effffff".subst("f", "jump", :g);    # returns "ejumpjumpjumpjumpjumpjump"
"blah".subst("z", "y", :g);          # returns "blah"

' 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.
FormatLanguages
reverse string Perl 5, Haskell
flip string
string.flip		 Raku
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() 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
⌽string APL
string.chars().rev().collect::<String>() Rust[40]
echo string | rev Unix
" Example in Smalltalk "
'hello' reversed             " returns 'olleh' "

# Example in Perl 5
reverse "hello"              # returns "olleh"

# Example in Raku
"hello".flip                 # 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
FormatLanguagesIf not found
InStrRev(«startpos,» string,substring) VB returns 0
instrrev(«startpos,» string,substring) FreeBASIC returns 0
rindex(string,substring«,startpos») Perl 5 returns −1
rindex(string,substring«,startpos»)
string.rindex(substring«,startpos»)		 Raku returns Nil
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
(⌽<\⌽substring⍷'string')⍳1 APL returns −1
string.rfind(substring) Rust[41] returns None
; 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 Perl 5
rindex("Hello mate", "e");               # returns 9
rindex("Hello mate", "e", 4);            # returns 1
rindex("word", "z");                     # returns -1

# Examples in Raku
"Hello mate".rindex("e");                # returns 9
"Hello mate".rindex("e", 4);             # returns 1
"word".rindex('z');                      # returns Nil

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


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).
FormatLanguages
string (string'Last - n + 1 .. string'Last) Ada
Right(string,n) VB
RIGHT$(string,n) BASIC
right(string,n) FreeBASIC, Ingres, Pick Basic
strcpy(string2, string+n) (n must not be greater than the length of string) C
string.Substring(string.Length()-n) C#
string[len(string)-n:] Go
string.substring(string.length()-n) Java
string.slice(-n) JavaScript[42]
right(string,n «,padchar») Rexx, Erlang
substr(string,-n) Perl 5, PHP
substr(string,*-n)
string.substr(*-n)		 Raku
string[-n:] Cobra, Python
${string_param: -n} (note the space after the colon) Bash
string[n] Pick Basic
(string-take-right string n) Scheme (SRFI 13)
string[-n..-1] Ruby
string[$-n .. $] D[43]
String.sub string (String.length string - n) n OCaml[26]
string.sub(string, -n)
(string):sub(-n)		 Lua
string last: n Smalltalk (Squeak, Pharo)
StringTake[string, -n] Mathematica[27]
string (1:n) COBOL
¯n↑string. APL
string[n..]
string.get(n..)		 Rust[28]
// Examples in Java; extract rightmost 4 characters
String str = "CarDoor";
str.substring(str.length()-4); // returns 'Door'

# Examples in Raku
"abcde".substr(*-3);          # returns "cde"
"abcde".substr(*-8);          # 'out of range' error

/* 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"


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.
FormatLanguages
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.
FormatLanguages
split(/separator/, string«, limit») Perl 5
split(separator, string«, limit»)
string.split(separator, «limit»)		 Raku
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
(separator≠string)⊂string or separator(≠⊆⊢)string in APL2 and Dyalog APL 16.0 respectively APL
string.split(separator)

string.split(limit, separator)

 Rust[44]
// 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 5
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')

# Examples in Raku
'Spam eggs spam spam and ham'.split(/spam/);  # (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.
FormatLanguages
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
string[startpos+(⍳numChars)-~⎕IO] APL
MID$(string, startpos, numChars) BASIC
substr(string, startpos, numChars) AWK (changes string), Perl 5,[45][46] PHP[45][46]
substr(string, startpos, numChars)
string.substr(startpos, numChars)		 Raku[47][48]
substr(string, startpos «,numChars, padChar») Rexx
string[startpos:endpos] Cobra, Python,[45][49] Go
string[startpos, numChars] Pick Basic
string[startpos, numChars]
string[startpos .. endpos-1]
string[startpos ... endpos]		 Ruby[45][49]
string[startpos .. endpos]
string[startpos len numChars]		 Seed7
string.slice(startpos«, endpos») JavaScript[45][49]
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[45][49]
string copyFrom: startpos to: endpos Smalltalk
string(startpos:endpos) Fortran
SUBSTRING(string FROM startpos «FOR numChars») SQL
StringTake[string, {startpos, endpos}] Mathematica[45][49]
string (startpos:numChars) COBOL
${string_param:startpos:numChars} Bash
string range string startpos endpos Tcl
string[startpos..endpos]
string.get(startpos..endpos)		 Rust[28]
// 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 Perl 5
substr("abc", 1, 1);       #  returns "b"
substr("abc", 1);          #  returns "bc"

# Examples in Raku
"abc".substr(1, 1);        #  returns "b"
"abc".substr(1);           #  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.
FormatLanguages
UCase(string) VB
ucase(string) FreeBASIC
toupper(string) AWK (changes string)
uc(string) Perl, Raku
string.uc Raku
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)[33] C++[50]
uppercase(string) Object Pascal (Delphi)
upcase(char) Object Pascal (Delphi) (operates on one character)
strtoupper(string) PHP
upper(string) Seed7
${string_param^^} (mnemonic: ^ is pointing up) Bash
echo "string" | tr 'a-z' 'A-Z' Unix
translate(string), or

UPPER variables, or
PARSE UPPER VAR SrcVar DstVar

 Rexx
string.upper() Python
upcase(string) Pick Basic
string.upcase Ruby[35]
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
string.to_uppercase() Rust[51]
// Example in C#
"Wiki means fast?".ToUpper();      // "WIKI MEANS FAST?"

# Example in Perl 5
uc("Wiki means fast?");             # "WIKI MEANS FAST?"

# Example in Raku
uc("Wiki means fast?");             # "WIKI MEANS FAST?"
"Wiki means fast?".uc;              # "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 usageLanguages
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+), Rust[52]
Trim(String) Pascal,[53] 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.trim Raku
trim(string) PHP, Raku
[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.

APL

APL can use regular expressions directly:

Trim←'^ +| +$'⎕R''

Alternatively, a functional approach combining Boolean masks that filter away leading and trailing spaces:

Trim←{⍵/⍨(∨\∧∘⌽∨\∘⌽)' '≠⍵}

Or reverse and remove leading spaces, twice:

Trim←{(∨\' '≠⍵)/⍵}∘⌽⍣2

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[54] 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:[55]

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

With boost's function named simply trim the input sequence is modified in-place, and returns no result.

Another open source C++ library Qt, has several trim variants, including a standard one:[56]

#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.[57]

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 Raku, the upcoming sister language of Perl, 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. 1 2 3 4 5 the index can be negative, which then indicates the number of places before the end of the string.
  2. ↑ In Rust, the str::chars method iterates over code points and the std::iter::Iterator::nth method on iterators returns the zero-indexed nth value from the iterator, or None.
  3. ↑ the index can not be negative, use *-N where N indicate the number of places before the end of the string.
  4. ↑ In C++, the overloaded operator<=> method on a string returns a std::strong_ordering object (otherwise std::weak_ordering): less, equal (same as equivalent), or greater.
  5. ↑ returns LESS, EQUAL, or GREATER
  6. ↑ returns LT, EQ, or GT
  7. ↑ returns .TRUE. or .FALSE.. These functions are based on the ASCII collating sequence.
  8. 1 2 IBM extension.
  9. ↑ In Rust, the Ord::cmp method on a string returns an Ordering: Less, Equal, or Greater.
  10. 1 2 3 4 5 6 In Rust, the operators == and != and the methods eq, ne are implemented by the PartialEq trait, and the operators <, >, <=, >= and the methods lt, gt, le, ge are implemented by the PartialOrd trait.
  11. ↑ The operators use the compiler's default collating sequence.
  12. ↑ modifies string1, which must have enough space to store the result
  13. ↑ In Rust, the + operator is implemented by the Add trait.
  14. ↑ See the str::contains method.
  15. ↑ See the std::basic_string::contains method.
  16. 1 2 startpos is IBM extension.
  17. 1 2 See the str::find method.
  18. ↑ startpos is IBM extension.
  19. ↑ "scan in Fortran Wiki". Fortranwiki.org. 2009-04-30. Retrieved 2013-08-18.
  20. ↑ "verify in Fortran Wiki". Fortranwiki.org. 2012-05-03. Retrieved 2013-08-18.
  21. ↑ formatstring must be a fixed literal at compile time for it to have the correct type.
  22. ↑ See std::format, which is imported by the Rust prelude so that it can be used under the name format.
  23. ↑ See the slice::join method.
  24. ↑ if n is larger than the length of the string, then in Debug mode ArrayRangeException is thrown, in Release mode, the behaviour is unspecified.
  25. ↑ if n is larger than the length of the string, Java will throw an IndexOutOfBoundsException
  26. 1 2 if n is larger than length of string, raises Invalid_argument
  27. 1 2 if n is larger than length of string, throw the message "StringTake::take:"
  28. 1 2 3 In Rust, strings are indexed in terms of byte offsets and there is a runtime panic if the index is out of bounds or if it would result in invalid UTF-8. A &str (string reference) can be indexed by various types of ranges, including Range (0..n), RangeFrom (n..), and RangeTo (..n) because they all implement the SliceIndex trait with str being the type being indexed. The str::get method is the non-panicking way to index. It returns None in the cases in which indexing would panic.
  29. ↑ Ruby lacks Unicode support
  30. ↑ See the str::len method.
  31. ↑ In Rust, the str::chars method iterates over code points and the std::iter::Iterator::count method on iterators consumes the iterator and returns the total number of elements in the iterator.
  32. ↑ operates on one character
  33. 1 2 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);
  34. ↑ 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
  35. 1 2 only ASCII characters as Ruby lacks Unicode support
  36. ↑ See the str::to_lowercase method.
  37. ↑ See the str::replace method.
  38. 1 2 3 4 5 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.
  39. ↑ third parameter is non-standard
  40. ↑ In Rust, the str::chars method iterates over code points, the std::iter::Iterator::rev method on reversible iterators (std::iter::DoubleEndedIterator) creates a reversed iterator, and the std::iter::Iterator::collect method consumes the iterator and creates a collection (which here is specified as a String with the turbofish syntax) from the iterator's elements.
  41. ↑ See the str::rfind method.
  42. ↑ "Annotated ES5". Es5.github.com. Archived from the original on 2013-01-28. Retrieved 2013-08-18.
  43. ↑ if n is larger than length of string, then in Debug mode ArrayRangeException is thrown, and unspecified behaviour in Release mode
  44. ↑ See the str::split and str::rsplit methods.
  45. 1 2 3 4 5 6 7 startpos can be negative, which indicates to start that number of places before the end of the string.
  46. 1 2 numChars can be negative, which indicates to end that number of places before the end of the string.
  47. ↑ startpos can not be negative, use * - startpos to indicate to start that number of places before the end of the string.
  48. ↑ numChars can not be negative, use * - numChars to indicate to end that number of places before the end of the string.
  49. 1 2 3 4 5 endpos can be negative, which indicates to end that number of places before the end of the string.
  50. ↑ 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
  51. ↑ In Rust, the str::to_uppercase method returns a newly allocated String with any lowercase characters changed to uppercase ones following the Unicode rules.
  52. ↑ In Rust, the str::trim method returns a reference to the original &str.
  53. ↑ "Trim – GNU Pascal priručnik". Gnu-pascal.de. Retrieved 2013-08-24.
  54. ↑ "String library comparison". And.org. Retrieved 2013-08-24.
  55. ↑ "Usage – 1.54.0". Boost.org. 2013-05-22. Retrieved 2013-08-24.
  56. ↑ Archived August 2, 2009, at the Wayback Machine
  57. ↑ dankamongmen. "sprezzos-kernel-packaging/changelog at master · dankamongmen/sprezzos-kernel-packaging · GitHub". Github.com. Retrieved 2016-05-29.
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