"String functions" redirects here. For string functions in formal language theory, see
String operations.
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.
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)[edit]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.
DefinitioncharAt(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,[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)[edit] Definition
compare(string1,string2)
returns integer. Description Compares two strings to each other. If they are equivalent, a zero is returned. Otherwise, most of these routines will return a positive or negative result corresponding to whether string1 is lexicographically greater than, or less than, respectively, than string2. The exceptions are the Scheme and Rexx routines which return the index of the first mismatch, and Smalltalk which answer a comparison code telling how the receiver sorts relative to string parameter. Format Languages IF string1<string2 THEN -1 ELSE ABS (string1>string2) FI
ALGOL 68 cmp(string1, string2)
Python 2 (string1 > string2) - (string1 < string2)
Python strcmp(string1, string2)
C, PHP std.string.cmp(string1, string2)
D StrComp(string1, string2)
VB, Object Pascal (Delphi) string1 cmp string2
Perl, 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 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)[edit] Definition
string1 OP string2
OR (compare string1 string2)
returns Boolean. Description Lexicographically compares two strings using a relational operator or function. Boolean result returned. Format Languages string1 OP string2
, where OP
can be any of =, <>, <, >, <=
and >=
Pascal, Object Pascal (Delphi), OCaml, Seed7, Standard ML, BASIC, VB, VB .NET, F# string1 OP string2
, where OP
can be any of =, /=, ≠, <, >, <=, ≤
and ≥
; Also: EQ, NE, LT, LE, GE
and GT
ALGOL 68 (stringOP? string1 string2)
, where OP
can be any of =, -ci=, <, -ci<, >, -ci>, <=, -ci<=, >=
and -ci>=
(operators starting with '-ci
' are case-insensitive) Scheme (stringOP string1 string2)
, where OP
can be any of =, -ci=, <>, -ci<>, <, -ci<, >, -ci>, <=, -ci<=, >=
and -ci>=
(operators starting with '-ci
' are case-insensitive) Scheme (SRFI 13) (stringOP string1 string2)
, where OP
can be any of =, -equal, /=, -not-equal, <, -lessp, >, -greaterp, <=, -not-greaterp, >=
and -not-lessp
(the verbal operators are case-insensitive) Common Lisp (stringOP string1 string2)
, where OP
can be any of =, /=, <, >, <=,
and >=
ISLISP string1 OP string2
, where OP
can be any of =, \=, <, >, <=
and >=
Rexx string1 OP string2
, where OP
can be any of =, ¬=, <, >, <=, >=, ¬<
and ¬>
PL/I string1 OP string2
, where OP
can be any of =, /=, <, >, <=
and >=
Ada string1 OP string2
, where OP
can be any of ==, /=, <, >, =<
and >=
Erlang string1 OP string2
, where OP
can be any of ==, /=, <, >, <=
and >=
Haskell string1 OP string2
, where OP
can be any of eq, ne, lt, gt, le
and ge
Perl, 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 nilDefinition
concatenate(string1,string2)
returns string. Description Concatenates (joins) two strings to each other, returning the combined string. Note that some languages like C have mutable strings, so really the second string is being appended to the first string and the mutated string is returned. Format Languages string1 & string2
Ada, FreeBASIC, Seed7, BASIC, VB, VB .NET, COBOL (between literals only) strcat(string1, string2)
C, C++ (char *
only)[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"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,[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 "
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 Languagesstring1 == 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
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
[ string1 = string2 ]
Bourne Shell string1 eq string2
Perl, Raku, Tcl string1.equals(string2)
Cobra, Java string1.Equals(string2)
C# string1 -eq string2
[string]::Equals(string1, string2)
Windows PowerShell [string1 isEqualToString:string2]
[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 0Definition
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»»)
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)
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
(search "e" "Hello mate") ; returns 1 (search "z" "word") ; returns NIL
"Hello mate".IndexOf("e"); // returns 1 "Hello mate".IndexOf("e", 4); // returns 9 "word".IndexOf("z"); // returns -1
"Hello, there!".index('e') # returns 1 "Hello, there!".index('z') # returns Nil
(use-modules (srfi srfi-13)) (string-contains "Hello mate" "e") ; returns 1 (string-contains "word" "z") ; returns #f
' Examples in InStr("Hello mate", "e") ' returns 2 InStr(5, "Hello mate", "e") ' returns 10 InStr("word", "z") ' returns 0
'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(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»)[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)
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]
Definitionformat(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
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" */
Tests if two strings are not equal. See also #Equality.
Format Languagesstring1 ne string2
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
[ string1 != string2 ]
Bourne Shell string1 -ne string2
-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
see #Find
see #Find
see #Find
see #rfind
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[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"}
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"
see #rfind
Definitionleft(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$(string,n)
BASIC, VB left(string,n)
VB, FreeBASIC, Ingres, Pick Basic strncpy(string2, string, n)
C standard library string.substr(0,n)
C++ (STL), Raku [string substringToIndex:n]
Objective-C (NSString *
only) (apply str (take n string))
Clojure string[0 .. n]
D[24] string:substr(string, start, length)
Erlang (subseq string 0 n)
Common Lisp string[:n]
Cobra, Go, Python left(string,n «,padchar»)
Rexx, Erlang string[0, n]
string[0..n - 1]
Ruby string[1, n]
Pick Basic string[ .. n]
Seed7 string.Substring(0,n)
VB .NET, C#, Windows PowerShell, F# leftstr(string, n)
Pascal, Object Pascal (Delphi) copy (string,1,n)
Turbo Pascal string.substring(0,n)
Java,[25] JavaScript (string-take string n)
Scheme (SRFI 13) take n string
Haskell String.extract (string, n, NONE)
Standard ML String.sub string 0 n
OCaml[26] string.[..n]
F# string.sub(string, 1, n)
(string):sub(1, n)
Lua string first: n
Smalltalk (Squeak, Pharo) string(:n)
Fortran StringTake[string, n]
Mathematica[27] string («FUNCTION» LENGTH(string) - n:n)
COBOL string.substring(0, n)
Cobra n↑string.
APL string[0..n]
string[..n]
string.get(0..n)
string.get(..n)
Rust[28]
# Example in Raku "Hello, there!".substr(0, 6); # returns "Hello,"
/* Examples in Rexx */ left("abcde", 3) /* returns "abc" */ left("abcde", 8) /* returns "abcde " */ left("abcde", 8, "*") /* returns "abcde***" */
; Examples in Scheme (use-modules (srfi srfi-13)) (string-take "abcde", 3) ; returns "abc" (string-take "abcde", 8) ; error
' Examples in Visual Basic Left("sandroguidi", 3) ' returns "san" Left("sandroguidi", 100) ' returns "sandroguidi"
see #length
Definitionlength(string)
returns an integer number Description Returns the length of a string (not counting the null terminator or any other of the string's internal structural information). An empty string returns a length of 0. Format Returns Languages string'Length
Ada UPB string
ALGOL 68 echo "${#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[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)
LEN_TRIM(string)
Fortran StringLength[string]
Mathematica «FUNCTION» LENGTH(string)
or
«FUNCTION» BYTE-LENGTH(string)
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
see #Find
Definitionlowercase(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[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?"
see #substring
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 Commentsstring.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');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[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]
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)
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"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[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"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»»)
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 0Definition
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[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"Definition <string>.rpartition(separator) Searches for the separator from right-to-left within the string then returns the sub-string before the separator; the separator; then the sub-string after the separator. Description Splits the given string by the right-most separator and returns the three substrings that together make the original. Format Languages
string.rpartition(separator)
Python, Ruby
# Examples in Python "Spam eggs spam spam and ham".rpartition('spam') ### ('Spam eggs spam ', 'spam', ' and ham') "Spam eggs spam spam and ham".rpartition('X') ### ("", "", 'Spam eggs spam spam and ham')
see #substring
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 Languagessplit(/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)
// 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)
see #Format
see #trim
See
CharAtfor base of startpos/endpos.
Definitionsubstring(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,[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****" */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)[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)
UPPER variables
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 string.uppercase()
Kotlin[51] 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[52]
// 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
or strip
is used to remove whitespace from the beginning, end, or both beginning and end, of a string.
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[53] Trim(String)
Pascal,[54] 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)
strip(string)
SAS string trim $string
Tcl TRIM(string)
TRIM(ADJUSTL(string))
Fortran TRIM(string)
SQL TRIM(string)
LTrim(string)
RTrim(String)
ColdFusion String.trim string
OCaml 4+
Other languages
In languages without a built-in trim function, it is usually simple to create a custom function which accomplishes the same task.
APL can use regular expressions directly:
Alternatively, a functional approach combining Boolean masks that filter away leading and trailing spaces:
Trim←{⍵/⍨(∨\∧∘⌽∨\∘⌽)' '≠⍵}
Or reverse and remove leading spaces, twice:
In AWK, one can use regular expressions to trim:
ltrim(v) = gsub(/^[ \t]+/, "", v) rtrim(v) = gsub(/[ \t]+$/, "", 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)); }
There is no standard trim function in C or C++. Most of the available string libraries[55] 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:[56]
#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:[57]
#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.[58]
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.
The trim algorithm in J is a functional description:
trim =. #~ [: (+./\ *. +./\.) ' '&~:
That is: filter (#~
) for non-space characters (' '&~:
) between leading (+./\
) and (*.
) trailing (+./\.
) spaces.
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 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
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 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.
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
.operator<=>
method on a string returns a std::strong_ordering
object (otherwise std::weak_ordering
): less
, equal
(same as equivalent
), or greater
..TRUE.
or .FALSE.
. These functions are based on the ASCII collating sequence.Ord::cmp
method on a string returns an Ordering
: Less
, Equal
, or Greater
.==
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.string1
, which must have enough space to store the result+
operator is implemented by the Add
trait.str::contains
method.std::basic_string::contains
method.str::find
method.startpos
is IBM extension.formatstring
must be a fixed literal at compile time for it to have the correct type.std::format
, which is imported by the Rust prelude so that it can be used under the name format
.slice::join
method.&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.str::len
method.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.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);
std::string
only, result is stored in string result
which is at least as long as string
, and may or may not be string
itselfstr::to_lowercase
method.str::replace
method.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.str::rfind
method.str::split
and str::rsplit
methods.startpos
can be negative, which indicates to start that number of places before the end of the string.numChars
can be negative, which indicates to end that number of places before the end of the string.startpos
can not be negative, use * - startpos to indicate to start that number of places before the end of the string.numChars
can not be negative, use * - numChars to indicate to end that number of places before the end of the string.endpos
can be negative, which indicates to end that number of places before the end of the string.std::string
only, result is stored in string result which is at least as long as string, and may or may not be string itselfstr::to_uppercase
method returns a newly allocated String
with any lowercase characters changed to uppercase ones following the Unicode rules.str::trim
method returns a reference to the original &str
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