# 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, APL, Julia, Pascal, Object Pascal (Delphi), Seed7 | 1 |
| string[i] | C, C++, C#, Cobra, D, FreeBASIC, Go, Python, PHP, Ruby, 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 | 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 | 0 |
| substr(string, i, 1) string.substr(i, 1) | Raku | 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 |
| string at: i | Smalltalk (w/ bounds checking) | 1 |
| string index string i | Tcl | 0 |
| StringTake[string, {i}] | Mathematica, Wolfram Language | 1 |
| string@i | Eiffel | 1 |
| string (i:1) | COBOL | 1 |
| ${string_param:i:1} | Bash | 0 |
| i⌷string | APL | 0 or 1 |

### Compare (integer result)

| Definition | compare(string$_1$,string$_2$) 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 string$_1$ is lexicographically greater than, or less than, respectively, than string$_2$. 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 string$_1$<string$_2$ THEN -1 ELSE ABS (string$_1$>string$_2$) FI | ALGOL 68 |
| cmp(string$_1$, string$_2$) | Python 2 |
| (string$_1$ > string$_2$) - (string$_1$ < string$_2$) | Python |
| strcmp(string$_1$, string$_2$) | C, PHP |
| std.string.cmp(string$_1$, string$_2$) | D |
| StrComp(string$_1$, string$_2$) | VB, Object Pascal (Delphi) |
| string$_1$ cmp string$_2$ | Perl, Raku |
| string$_1$ compare: string$_2$ | Smalltalk (Squeak, Pharo) |
| string$_1$ <=> string$_2$ | Ruby, C++ (STL, C++20) |
| string$_1$.compare(string$_2$) | C++ (STL), Swift (Foundation) |
| compare(string$_1$, string$_2$) | Rexx, Seed7 |
| CompareStr(string$_1$, string$_2$) | Pascal, Object Pascal (Delphi) |
| string$_1$.compareTo(string$_2$) | Cobra, Java |
| string$_1$.CompareTo(string$_2$) | VB .NET, C#, F# |
| (compare string$_1$ string$_2$) | Clojure |
| (string= string$_1$ string$_2$) | Common Lisp |
| (string-compare string$_1$ string$_2$ p< p= p>) | Scheme (SRFI 13) |
| (string= string$_1$ string$_2$) | ISLISP |
| compare string$_1$ string$_2$ | OCaml |
| String.compare (string$_1$, string$_2$) | Standard ML |
| compare string$_1$ string$_2$ | Haskell |
| [string]::Compare(string$_1$, string$_2$) | Windows PowerShell |
| [string$_1$ compare:string$_2$] | Objective-C (NSString * only) |
| LLT(string$_1$,string$_2$) LLE(string$_1$,string$_2$) LGT(string$_1$,string$_2$) LGE(string$_1$,string$_2$) | Fortran |
| string$_1$.localeCompare(string$_2$) | JavaScript |
| bytes.Compare(byte(string$_1$),byte(string$_2$)) | Go |
| string compare string$_1$ string$_2$ | Tcl |
| compare(string$_1$,string$_2$,count) | PL/I |
| string$_1$.cmp(string$_2$) | Rust |

### Compare (relational operator-based, Boolean result)

| Definition | string$_1$ OP string$_2$ OR (compare string$_1$ string$_2$) returns Boolean. |
| Description | Lexicographically compares two strings using a relational operator or function. Boolean result returned. |
| Format | Languages |
| string$_1$ OP string$_2$, where OP can be any of =, <>, <, >, <= and >= | Pascal, Object Pascal (Delphi), OCaml, Seed7, Standard ML, BASIC, VB, VB .NET, F# |
| string$_1$ OP string$_2$, where OP can be any of =, /=, ≠, <, >, <=, ≤ and ≥; Also: EQ, NE, LT, LE, GE and GT | ALGOL 68 |
| (stringOP? string$_1$ string$_2$), where OP can be any of =, -ci=, <, -ci<, >, -ci>, <=, -ci<=, >= and -ci>= (operators starting with '-ci' are case-insensitive) | Scheme |
| (stringOP string$_1$ string$_2$), where OP can be any of =, -ci=, <>, -ci<>, <, -ci<, >, -ci>, <=, -ci<=, >= and -ci>= (operators starting with '-ci' are case-insensitive) | Scheme (SRFI 13) |
| (stringOP string$_1$ string$_2$), 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 string$_1$ string$_2$), where OP can be any of =, /=, <, >, <=, and >= | ISLISP |
| string$_1$ OP string$_2$, where OP can be any of =, \=, <, >, <= and >= | Rexx |
| string$_1$ OP string$_2$, where OP can be any of =, ¬=, <, >, <=, >=, ¬< and ¬> | PL/I |
| string$_1$ OP string$_2$, where OP can be any of =, /=, <, >, <= and >= | Ada |
| string$_1$ OP string$_2$, where OP can be any of ==, /=, <, >, =< and >= | Erlang |
| string$_1$ OP string$_2$, where OP can be any of ==, /=, <, >, <= and >= | Haskell |
| string$_1$ OP string$_2$, where OP can be any of eq, ne, lt, gt, le and ge | Perl, Raku |
| string$_1$ OP string$_2$, where OP can be any of ==, !=, <, >, <= and >= | C++ (STL), C#, D, Go, JavaScript, Python, PHP, Ruby, Rust, Swift |
| string$_1$ OP string$_2$, 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 |
| string$_1$ OP string$_2$, where OP can be any of ==, ~=, <, >, <= and >= | Lua |
| string$_1$ OP string$_2$, where OP can be any of =, ~=, <, >, <= and >= | Smalltalk |
| string$_1$ OP string$_2$, where OP can be any of ==, /=, <, >, <= and >=; Also: .EQ., .NE., .LT., .LE., .GT. and .GE. | Fortran. |
| string$_1$ OP string$_2$ where OP can be any of =, <>, <, >, <=, >= as well as worded equivalents | COBOL |
| string$_1$ OP string$_2$ where OP can be any of ==, <>, <, >, <= and >= | Cobra |
| string$_1$ OP string$_2$ 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 |
| string$_1$.METHOD(string$_2$) where METHOD is any of eq, ne, gt, lt, ge, le | Rust |

### Concatenation

| Definition | concatenate(string$_1$,string$_2$) 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 |
| string$_1$ & string$_2$ | Ada, FreeBASIC, Seed7, BASIC, VB, VB .NET, COBOL (between literals only) |
| strcat(string$_1$, string$_2$) | C, C++ (char * only) |
| string$_1$ . string$_2$ | Perl, PHP |
| string$_1$ + string$_2$ | ALGOL 68, C++ (STL), C#, Cobra, FreeBASIC, Go, Pascal, Object Pascal (Delphi), Java, JavaScript, Windows PowerShell, Python, Ruby, Rust, F#, Swift, Turing, VB |
| string$_1$ ~ string$_2$ | D, Raku |
| (string-append string$_1$ string$_2$) | Scheme, ISLISP |
| (concatenate 'string string$_1$ string$_2$) | Common Lisp |
| (str string$_1$ string$_2$) | Clojure |
| string$_1$ || string$_2$ | Rexx, SQL, PL/I |
| string$_1$ // string$_2$ | Fortran |
| string$_1$ ++ string$_2$ | Erlang, Haskell |
| string$_1$ ^ string$_2$ | OCaml, Standard ML, F# |
| [string$_1$ stringByAppendingString:string$_2$] | Objective-C (NSString * only) |
| string$_1$ .. string$_2$ | Lua |
| string$_1$ , string$_2$ | Smalltalk, APL |
| string$_1$ string$_2$ | SNOBOL |
| string$_1$string$_2$ | Bash |
| string$_1$ <> string$_2$ | Mathematica |
| concat string$_1$ string$_2$ | Tcl |

### 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+), Raku, Rust, C++ (C++23) |
| 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 |
| 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 |

### 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 |
| string$_1$ == string$_2$ | Python, C++ (STL), C#, Cobra, Go, JavaScript (similarity), PHP (similarity), Ruby, Rust, Erlang, Haskell, Lua, D, Mathematica, Swift |
| string$_1$ === string$_2$ | JavaScript, PHP |
| string$_1$ == string$_2$ string$_1$ .EQ. string$_2$ | Fortran |
| strcmp(string$_1$, string$_2$) == 0 | C |
| (string=? string$_1$ string$_2$) | Scheme |
| (string= string$_1$ string$_2$) | Common Lisp, ISLISP |
| string$_1$ = string$_2$ | ALGOL 68, Ada, Object Pascal (Delphi), OCaml, Pascal, Rexx, Seed7, Standard ML, BASIC, VB, VB .NET, F#, Smalltalk, PL/I, COBOL |
| test string$_1$ = string$_2$ [ string$_1$ = string$_2$ ] | Bourne Shell |
| string$_1$ eq string$_2$ | Perl, Raku, Tcl |
| string$_1$.equals(string$_2$) | Cobra, Java |
| string$_1$.Equals(string$_2$) | C# |
| string$_1$ -eq string$_2$ [string]::Equals(string$_1$, string$_2$) | Windows PowerShell |
| [string$_1$ isEqualToString:string$_2$] [string$_1$ isEqual:string$_2$] | Objective-C (NSString * only) |
| string$_1$ ≡ string$_2$ | APL |
| string$_1$.eq(string$_2$) | Rust |

### 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 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»») | Python | 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 | 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 | 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 |
| 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») position = VERIFY (string, set «, back» «, kind») | 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 | 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 | returns None |
^a Given a set of characters, SCAN returns the position of the first character found, while VERIFY returns the position of the first character that does not belong to the set.

### 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 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 formatstring ⎕FMT items | APL | APL |
| format!(formatstring, items) | Rust | Python |

### Inequality

Tests if two strings are not equal. See also #Equality.
| Format | Languages |
| string$_1$ ne string$_2$ string$_1$ NE string$_2$ | ALGOL 68 – note: the operator "ne" is literally in bold type-font. |
| string$_1$ /= string$_2$ | ALGOL 68, Ada, Erlang, Fortran, Haskell |
| string$_1$ <> string$_2$ | BASIC, VB, VB .NET, Pascal, Object Pascal (Delphi), OCaml, PHP, Seed7, Standard ML, F#, COBOL, Cobra, Python 2 (deprecated) |
| string$_1$ # string$_2$ | BASIC (some implementations) |
| string$_1$ ne string$_2$ | Perl, Raku |
| (string<> string$_1$ string$_2$) | Scheme (SRFI 13) |
| (string/= string$_1$ string$_2$) | Common Lisp |
| (string/= string$_1$ string$_2$) | ISLISP |
| (not= string$_1$ string$_2$) | Clojure |
| string$_1$ != string$_2$ | C++ (STL), C#, Go, JavaScript (not similar), PHP (not similar), Python, Ruby, Rust, Swift, D, Mathematica |
| string$_1$ !== string$_2$ | JavaScript, PHP |
| string$_1$ \= string$_2$ | Rexx |
| string$_1$ ¬= string$_2$ | PL/I |
| test string$_1$ != string$_2$ [ string$_1$ != string$_2$ ] | Bourne Shell |
| string$_1$ -ne string$_2$ -not [string]::Equals(string$_1$, string$_2$) | Windows PowerShell |
| string$_1$ ~= string$_2$ | Lua, Smalltalk |
| string$_1$ ≢ string$_2$ | APL |
| string$_1$.ne(string$_2$) | Rust |

### 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, 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 |
| (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"} 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 |

### 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, 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 |
| 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, 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 |
| 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 |
| 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 |

### 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 |
| 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 | 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) 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 |
| string.chars.count | Number of Unicode code points | Rust |

### 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, Raku |
| string.lc | Raku |
| tolower(char) | C |
| std.string.toLower(string) | D |
| transform(string.begin, string.end, result.begin, ::tolower) | C++ |
| 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 |
| 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 |
| ToLowerCase[string] | Mathematica |
| «FUNCTION» LOWER-CASE(string) | COBOL |
| string.toLower | Cobra |
| string tolower string | Tcl |
| string.to_lowercase | Rust |

### 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 | Comments |
| 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 |

### 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 |
| 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 |
| string.replaceAll(find_regex, replace) | Java |
| string.gsub(find, replace) | Ruby |
| string =~ s/find_regex/replace/g | Perl 5 |
| string.subst(find, replace, :g) | Raku |
| string.replace(find, replace, "g") string.replace(/find_regex/g, replace) | JavaScript |
| echo "string" | sed 's/find_regex/replace/g' | Unix |
| ${string_param//find_pattern/replace} | Bash |
| string.replace(find, replace) string -replace find_regex, replace | 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 |

### reverse

| Definition | reverse(string) |
| Description | Reverses the order of the characters in the string. |
| Format | Languages |
| 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 |
| echo string | rev | Unix |

### 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 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»») | Python | 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 | returns None |

### 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, 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 |
| 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 |
| String.sub string (String.length string - n) n | OCaml |
| string.sub(string, -n) (string):sub(-n) | Lua |
| string last: n | Smalltalk (Squeak, Pharo) |
| StringTake[string, -n] | Mathematica |
| string (1:n) | COBOL |
| ¯n↑string. | APL |
| string[n..] string.get(n..) | Rust |

### 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 |

### 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 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 in APL2 separator(≠⊆⊢)string in Dyalog APL 16.0 | APL |
| string.split(separator) string.split(limit, separator) | Rust |

### 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 |
| string[startpos+(⍳numChars)-~⎕IO] | APL |
| MID$(string, startpos, numChars) | BASIC |
| substr(string, startpos, numChars) | AWK (changes string), Perl 5, PHP |
| substr(string, startpos, numChars) string.substr(startpos, numChars) | Raku |
| substr(string, startpos «,numChars, padChar») | Rexx |
| string[startpos:endpos] | Cobra, Python, Go |
| string[startpos, numChars] | Pick Basic |
| string[startpos, numChars] string[startpos .. endpos-1] string[startpos ... endpos] | Ruby |
| string[startpos .. endpos] string[startpos len numChars] | Seed7 |
| string.slice(startpos«, endpos») | JavaScript |
| 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 |
| string copyFrom: startpos to: endpos | Smalltalk |
| string(startpos:endpos) | Fortran |
| SUBSTRING(string FROM startpos «FOR numChars») | SQL |
| StringTake[string, {startpos, endpos}] | Mathematica |
| string (startpos:numChars) | COBOL |
| ${string_param:startpos:numChars} | Bash |
| string range string startpos endpos | Tcl |
| string[startpos..endpos] string.get(startpos..endpos) | Rust |

### 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, 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) | C++ |
| 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) UPPER variables PARSE UPPER VAR SrcVar DstVar | Rexx |
| string.upper | Python |
| upcase(string) | Pick Basic |
| string.upcase | Ruby |
| 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 |
| string.uppercase | Kotlin |
| 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 |

### 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+), Rust |
| Trim(String) | Pascal, 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 string.lstrip 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) TRIM(ADJUSTL(string)) | Fortran |
| TRIM(string) | SQL |
| TRIM(string) LTrim(string) 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:
Alternatively, a functional approach combining Boolean masks that filter away leading and trailing spaces:
Or reverse and remove leading spaces, twice:

#### AWK

In AWK, one can use regular expressions to trim:
or:

#### C/C++

There is no standard trim function in C or C++. Most of the available string libraries 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:
The open source C++ library Boost has several trim variants, including a standard one:
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:
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.

#### Haskell

A trim algorithm in Haskell:
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:
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:

#### Perl

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

#### 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:

#### 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:
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.