View Source string (stdlib v6.0)

String processing functions.

This module provides functions for string processing.

A string in this module is represented by unicode:chardata/0, that is, a list of codepoints, binaries with UTF-8-encoded codepoints (UTF-8 binaries), or a mix of the two.

"abcd"               is a valid string
<<"abcd">>           is a valid string
["abcd"]             is a valid string
<<"abc..åäö"/utf8>>  is a valid string
<<"abc..åäö">>       is NOT a valid string,
                     but a binary with Latin-1-encoded codepoints
[<<"abc">>, "..åäö"] is a valid string
[atom]               is NOT a valid string

This module operates on grapheme clusters. A grapheme cluster is a user-perceived character, which can be represented by several codepoints.

"å"  [229] or [97, 778]
"e̊"  [101, 778]

The string length of "ß↑e̊" is 3, even though it is represented by the codepoints [223,8593,101,778] or the UTF-8 binary <<195,159,226,134,145,101,204,138>>.

Grapheme clusters for codepoints of class prepend and non-modern (or decomposed) Hangul is not handled for performance reasons in find/3, replace/3, split/2, split/3 and trim/3.

Splitting and appending strings is to be done on grapheme clusters borders. There is no verification that the results of appending strings are valid or normalized.

Most of the functions expect all input to be normalized to one form, see for example unicode:characters_to_nfc_list/1.

Language or locale specific handling of input is not considered in any function.

The functions can crash for non-valid input strings. For example, the functions expect UTF-8 binaries but not all functions verify that all binaries are encoded correctly.

Unless otherwise specified the return value type is the same as the input type. That is, binary input returns binary output, list input returns a list output, and mixed input can return a mixed output.

1> string:trim("  sarah  ").
"sarah"
2> string:trim(<<"  sarah  ">>).
<<"sarah">>
3> string:lexemes("foo bar", " ").
["foo","bar"]
4> string:lexemes(<<"foo bar">>, " ").
[<<"foo">>,<<"bar">>]

This module has been reworked in Erlang/OTP 20 to handle unicode:chardata/0 and operate on grapheme clusters. The old functions that only work on Latin-1 lists as input are still available but should not be used, they will be deprecated in a future release.

Notes

Some of the general string functions can seem to overlap each other. The reason is that this string package is the combination of two earlier packages and all functions of both packages have been retained.

Summary

Types

A user-perceived character, consisting of one or more codepoints.

Functions

Converts String to a case-agnostic comparable string. Function casefold/1 is preferred over lowercase/1 when two strings are to be compared for equality. See also equal/4.

Returns a string where any trailing \n or \r\n have been removed from String.

Returns true if A and B are equal, otherwise false.

Removes anything before SearchPattern in String and returns the remainder of the string or nomatch if SearchPattern is not found. Dir, which can be leading or trailing, indicates from which direction characters are to be searched.

Returns true if String is the empty string, otherwise false.

Returns a float between +0.0 and 1.0 representing the Jaro similarity between the given strings. Strings with many letters in common relative to their lengths will score closer to 1.0.

Returns the number of grapheme clusters in String.

Returns a list of lexemes in String, separated by the grapheme clusters in SeparatorList.

Converts String to lowercase.

Returns the first codepoint in String and the rest of String in the tail. Returns an empty list if String is empty or an {error, String} tuple if the next byte is invalid.

Returns the first grapheme cluster in String and the rest of String in the tail. Returns an empty list if String is empty or an {error, String} tuple if the next byte is invalid.

Returns lexeme number N in String, where lexemes are separated by the grapheme clusters in SeparatorList.

Pads String to Length with grapheme cluster Char. Dir, which can be leading, trailing, or both, indicates where the padding should be added.

If Prefix is the prefix of String, removes it and returns the remainder of String, otherwise returns nomatch.

Replaces SearchPattern in String with Replacement. Where, indicates whether the leading, the trailing or all encounters of SearchPattern are to be replaced.

Returns the reverse list of the grapheme clusters in String.

Returns a substring of String of at most Length grapheme clusters, starting at position Start.

Splits String where SearchPattern is encountered and return the remaining parts. Where, default leading, indicates whether the leading, the trailing or all encounters of SearchPattern will split String.

Takes characters from String as long as the characters are members of set Characters or the complement of set Characters. Dir, which can be leading or trailing, indicates from which direction characters are to be taken.

Converts String to titlecase.

Argument String is expected to start with a valid text represented float (the digits are ASCII values). Remaining characters in the string after the float are returned in Rest.

Converts String to a list of grapheme clusters.

Argument String is expected to start with a valid text represented integer (the digits are ASCII values). Remaining characters in the string after the integer are returned in Rest.

Equivalent to trim(String, Dir, Whitespace}) where Whitespace is the set of nonbreakable whitespace codepoints, defined as Pattern_White_Space in Unicode Standard Annex #31.

Returns a string, where leading or trailing, or both, Characters have been removed.

Converts String to uppercase.

Obsolete API functions

Returns a string, where String is centered in the string and surrounded by blanks or Character. The resulting string has length Number.

Returns a string consisting of Number characters Character. Optionally, the string can end with string Tail.

Returns the index of the first occurrence of Character in String. Returns 0 if Character does not occur.

Concatenates String1 and String2 to form a new string String3, which is returned.

Returns a string containing String repeated Number times.

Returns the length of the maximum initial segment of String, which consists entirely of characters not from Chars.

Returns a string with the elements of StringList separated by the string in Separator.

Returns String with the length adjusted in accordance with Number. The left margin is fixed. If length(String) < Number, then String is padded with blanks or Characters.

Returns the number of characters in String.

Returns the index of the last occurrence of Character in String. Returns 0 if Character does not occur.

Returns String with the length adjusted in accordance with Number. The right margin is fixed. If the length of (String) < Number, then String is padded with blanks or Characters.

Returns the position where the last occurrence of SubString begins in String. Returns 0 if SubString does not exist in String.

Returns the length of the maximum initial segment of String, which consists entirely of characters from Chars.

Returns the position where the first occurrence of SubString begins in String. Returns 0 if SubString does not exist in String.

Returns a string, where leading or trailing, or both, blanks or a number of Character have been removed.

Returns a substring of String, starting at position Start to the end of the string, or to and including position Stop.

Returns the word in position Number of String. Words are separated by blanks or Characters.

Returns a substring of String, starting at position Start, and ending at the end of the string or at length Length.

The specified string or character is case-converted. Notice that the supported character set is ISO/IEC 8859-1 (also called Latin 1); all values outside this set are unchanged.

The specified string or character is case-converted. Notice that the supported character set is ISO/IEC 8859-1 (also called Latin 1); all values outside this set are unchanged.

Returns a list of tokens in String, separated by the characters in SeparatorList.

Returns the number of words in String, separated by blanks or Character.

Types

Link to this type

direction()

View Source (not exported)
-type direction() :: leading | trailing.
-type grapheme_cluster() :: char() | [char()].

A user-perceived character, consisting of one or more codepoints.

Functions

Link to this function

casefold(String)

View Source (since OTP 20.0)
-spec casefold(String :: unicode:chardata()) -> unicode:chardata().

Converts String to a case-agnostic comparable string. Function casefold/1 is preferred over lowercase/1 when two strings are to be compared for equality. See also equal/4.

Example:

1> string:casefold("Ω and ẞ SHARP S").
"ω and ss sharp s"
Link to this function

chomp(String)

View Source (since OTP 20.0)
-spec chomp(String :: unicode:chardata()) -> unicode:chardata().

Returns a string where any trailing \n or \r\n have been removed from String.

Example:

182> string:chomp(<<"\nHello\n\n">>).
<<"\nHello">>
183> string:chomp("\nHello\r\r\n").
"\nHello\r"
Link to this function

equal(A, B)

View Source (since OTP 20.0)
-spec equal(A, B) -> boolean() when A :: unicode:chardata(), B :: unicode:chardata().

Equivalent to equal(A, B, true)

Link to this function

equal(A, B, IgnoreCase)

View Source (since OTP 20.0)
-spec equal(A, B, IgnoreCase) -> boolean()
         when A :: unicode:chardata(), B :: unicode:chardata(), IgnoreCase :: boolean().

Equivalent to equal(A, B, IgnoreCase, none)

Link to this function

equal(A, B, IgnoreCase, Norm)

View Source (since OTP 20.0)
-spec equal(A, B, IgnoreCase, Norm) -> boolean()
         when
             A :: unicode:chardata(),
             B :: unicode:chardata(),
             IgnoreCase :: boolean(),
             Norm :: none | nfc | nfd | nfkc | nfkd.

Returns true if A and B are equal, otherwise false.

If IgnoreCase is true the function does casefolding on the fly before the equality test.

If Norm is not none the function applies normalization on the fly before the equality test. There are four available normalization forms: nfc, nfd, nfkc, and nfkd.

Example:

1> string:equal("åäö", <<"åäö"/utf8>>).
true
2> string:equal("åäö", unicode:characters_to_nfd_binary("åäö")).
false
3> string:equal("åäö", unicode:characters_to_nfd_binary("ÅÄÖ"), true, nfc).
true
Link to this function

find(String, SearchPattern)

View Source (since OTP 20.0)
-spec find(String, SearchPattern) -> unicode:chardata() | nomatch
        when String :: unicode:chardata(), SearchPattern :: unicode:chardata().

Equivalent to find(String, SearchPattern, leading)

Link to this function

find(String, SearchPattern, Dir)

View Source (since OTP 20.0)
-spec find(String, SearchPattern, Dir) -> unicode:chardata() | nomatch
        when String :: unicode:chardata(), SearchPattern :: unicode:chardata(), Dir :: direction().

Removes anything before SearchPattern in String and returns the remainder of the string or nomatch if SearchPattern is not found. Dir, which can be leading or trailing, indicates from which direction characters are to be searched.

Example:

1> string:find("ab..cd..ef", ".").
"..cd..ef"
2> string:find(<<"ab..cd..ef">>, "..", trailing).
<<"..ef">>
3> string:find(<<"ab..cd..ef">>, "x", leading).
nomatch
4> string:find("ab..cd..ef", "x", trailing).
nomatch
Link to this function

is_empty(String)

View Source (since OTP 20.0)
-spec is_empty(String :: unicode:chardata()) -> boolean().

Returns true if String is the empty string, otherwise false.

Example:

1> string:is_empty("foo").
false
2> string:is_empty(["",<<>>]).
true
Link to this function

jaro_similarity(String1, String2)

View Source (since OTP 27.0)
-spec jaro_similarity(String1, String2) -> Similarity
                   when
                       String1 :: unicode:chardata(),
                       String2 :: unicode:chardata(),
                       Similarity :: float().

Returns a float between +0.0 and 1.0 representing the Jaro similarity between the given strings. Strings with many letters in common relative to their lengths will score closer to 1.0.

The Jaro distance between two strings can be calculated with JaroDistance = 1.0-JaroSimilarity.

Example:

1> string:jaro_similarity("ditto", "ditto").
1.0
2> string:jaro_similarity("foo", "bar").
+0.0
3> string:jaro_similarity("michelle", "michael").
0.8690476190476191
4> string:jaro_similarity(<<"Édouard"/utf8>>, <<"Claude">>).
0.5317460317460317
Link to this function

length(String)

View Source (since OTP 20.0)
-spec length(String :: unicode:chardata()) -> non_neg_integer().

Returns the number of grapheme clusters in String.

Example:

1> string:length("ß↑e̊").
3
2> string:length(<<195,159,226,134,145,101,204,138>>).
3
Link to this function

lexemes(String, SeparatorList)

View Source (since OTP 20.0)
-spec lexemes(String :: unicode:chardata(), SeparatorList :: [grapheme_cluster()]) ->
           [unicode:chardata()].

Returns a list of lexemes in String, separated by the grapheme clusters in SeparatorList.

Notice that, as shown in this example, two or more adjacent separator graphemes clusters in String are treated as one. That is, there are no empty strings in the resulting list of lexemes. See also split/3 which returns empty strings.

Notice that [$\r,$\n] is one grapheme cluster.

Example:

1> string:lexemes("abc de̊fxxghix jkl\r\nfoo", "x e" ++ [[$\r,$\n]]).
["abc","de̊f","ghi","jkl","foo"]
2> string:lexemes(<<"abc de̊fxxghix jkl\r\nfoo"/utf8>>, "x e" ++ [$\r,$\n]).
[<<"abc">>,<<"de̊f"/utf8>>,<<"ghi">>,<<"jkl\r\nfoo">>]
Link to this function

lowercase(String)

View Source (since OTP 20.0)
-spec lowercase(String :: unicode:chardata()) -> unicode:chardata().

Converts String to lowercase.

Notice that function casefold/1 should be used when converting a string to be tested for equality.

Example:

2> string:lowercase(string:uppercase("Michał")).
"michał"
Link to this function

next_codepoint(String)

View Source (since OTP 20.0)
-spec next_codepoint(String :: unicode:chardata()) ->
                  maybe_improper_list(char(), unicode:chardata()) | {error, unicode:chardata()}.

Returns the first codepoint in String and the rest of String in the tail. Returns an empty list if String is empty or an {error, String} tuple if the next byte is invalid.

Example:

1> string:next_codepoint(unicode:characters_to_binary("e̊fg")).
[101|<<"̊fg"/utf8>>]
Link to this function

next_grapheme(String)

View Source (since OTP 20.0)
-spec next_grapheme(String :: unicode:chardata()) ->
                 maybe_improper_list(grapheme_cluster(), unicode:chardata()) |
                 {error, unicode:chardata()}.

Returns the first grapheme cluster in String and the rest of String in the tail. Returns an empty list if String is empty or an {error, String} tuple if the next byte is invalid.

Example:

1> string:next_grapheme(unicode:characters_to_binary("e̊fg")).
["e̊"|<<"fg">>]
Link to this function

nth_lexeme(String, N, SeparatorList)

View Source (since OTP 20.0)
-spec nth_lexeme(String, N, SeparatorList) -> unicode:chardata()
              when
                  String :: unicode:chardata(),
                  N :: non_neg_integer(),
                  SeparatorList :: [grapheme_cluster()].

Returns lexeme number N in String, where lexemes are separated by the grapheme clusters in SeparatorList.

Example:

1> string:nth_lexeme("abc.de̊f.ghiejkl", 3, ".e").
"ghi"
Link to this function

pad(String, Length)

View Source (since OTP 20.0)
-spec pad(String, Length) -> unicode:charlist() when String :: unicode:chardata(), Length :: integer().

Equivalent to pad(String, Length, trailing)

Link to this function

pad(String, Length, Dir)

View Source (since OTP 20.0)
-spec pad(String, Length, Dir) -> unicode:charlist()
       when String :: unicode:chardata(), Length :: integer(), Dir :: direction() | both.

Equivalent to pad(String, Length, Dir, $ )

Link to this function

pad(String, Length, Dir, Char)

View Source (since OTP 20.0)
-spec pad(String, Length, Dir, Char) -> unicode:charlist()
       when
           String :: unicode:chardata(),
           Length :: integer(),
           Dir :: direction() | both,
           Char :: grapheme_cluster().

Pads String to Length with grapheme cluster Char. Dir, which can be leading, trailing, or both, indicates where the padding should be added.

Example:

1> string:pad(<<"He̊llö"/utf8>>, 8).
[<<72,101,204,138,108,108,195,182>>,32,32,32]
2> io:format("'~ts'~n",[string:pad("He̊llö", 8, leading)]).
'   He̊llö'
3> io:format("'~ts'~n",[string:pad("He̊llö", 8, both)]).
' He̊llö  '
Link to this function

prefix(String, Prefix)

View Source (since OTP 20.0)
-spec prefix(String :: unicode:chardata(), Prefix :: unicode:chardata()) -> nomatch | unicode:chardata().

If Prefix is the prefix of String, removes it and returns the remainder of String, otherwise returns nomatch.

Example:

1> string:prefix(<<"prefix of string">>, "pre").
<<"fix of string">>
2> string:prefix("pre", "prefix").
nomatch
Link to this function

replace(String, SearchPattern, Replacement)

View Source (since OTP 20.0)
-spec replace(String, SearchPattern, Replacement) -> [unicode:chardata()]
           when
               String :: unicode:chardata(),
               SearchPattern :: unicode:chardata(),
               Replacement :: unicode:chardata().

Equivalent to replace(String, SearchPattern, Replacement, leading)

Link to this function

replace(String, SearchPattern, Replacement, Where)

View Source (since OTP 20.0)
-spec replace(String, SearchPattern, Replacement, Where) -> [unicode:chardata()]
           when
               String :: unicode:chardata(),
               SearchPattern :: unicode:chardata(),
               Replacement :: unicode:chardata(),
               Where :: direction() | all.

Replaces SearchPattern in String with Replacement. Where, indicates whether the leading, the trailing or all encounters of SearchPattern are to be replaced.

Can be implemented as:

lists:join(Replacement, split(String, SearchPattern, Where)).

Example:

1> string:replace(<<"ab..cd..ef">>, "..", "*").
[<<"ab">>,"*",<<"cd..ef">>]
2> string:replace(<<"ab..cd..ef">>, "..", "*", all).
[<<"ab">>,"*",<<"cd">>,"*",<<"ef">>]
Link to this function

reverse(String)

View Source (since OTP 20.0)
-spec reverse(String :: unicode:chardata()) -> [grapheme_cluster()].

Returns the reverse list of the grapheme clusters in String.

Example:

1> Reverse = string:reverse(unicode:characters_to_nfd_binary("ÅÄÖ")).
[[79,776],[65,776],[65,778]]
2> io:format("~ts~n",[Reverse]).
ÖÄÅ
Link to this function

slice(String, Start)

View Source (since OTP 20.0)
-spec slice(String, Start) -> Slice
         when
             String :: unicode:chardata(), Start :: non_neg_integer(), Slice :: unicode:chardata().

Equivalent to slice(String, Length, infinity)

Link to this function

slice(String, Start, Length)

View Source (since OTP 20.0)
-spec slice(String, Start, Length) -> Slice
         when
             String :: unicode:chardata(),
             Start :: non_neg_integer(),
             Length :: infinity | non_neg_integer(),
             Slice :: unicode:chardata().

Returns a substring of String of at most Length grapheme clusters, starting at position Start.

Example:

1> string:slice(<<"He̊llö Wörld"/utf8>>, 4).
<<"ö Wörld"/utf8>>
2> string:slice(["He̊llö ", <<"Wörld"/utf8>>], 4,4).
"ö Wö"
3> string:slice(["He̊llö ", <<"Wörld"/utf8>>], 4,50).
"ö Wörld"
Link to this function

split(String, SearchPattern)

View Source (since OTP 20.0)
-spec split(String, SearchPattern) -> [unicode:chardata()]
         when String :: unicode:chardata(), SearchPattern :: unicode:chardata().

Equivalent to split(String, SearchPattern, leading)

Link to this function

split(String, SearchPattern, Where)

View Source (since OTP 20.0)
-spec split(String, SearchPattern, Where) -> [unicode:chardata()]
         when
             String :: unicode:chardata(),
             SearchPattern :: unicode:chardata(),
             Where :: direction() | all.

Splits String where SearchPattern is encountered and return the remaining parts. Where, default leading, indicates whether the leading, the trailing or all encounters of SearchPattern will split String.

Example:

0> string:split("ab..bc..cd", "..").
["ab","bc..cd"]
1> string:split(<<"ab..bc..cd">>, "..", trailing).
[<<"ab..bc">>,<<"cd">>]
2> string:split(<<"ab..bc....cd">>, "..", all).
[<<"ab">>,<<"bc">>,<<>>,<<"cd">>]
Link to this function

take(String, Characters)

View Source (since OTP 20.0)
-spec take(String, Characters) -> {Leading, Trailing}
        when
            String :: unicode:chardata(),
            Characters :: [grapheme_cluster()],
            Leading :: unicode:chardata(),
            Trailing :: unicode:chardata().

Equivalent to take(String, Characters, false)

Link to this function

take(String, Characters, Complement)

View Source (since OTP 20.0)
-spec take(String, Characters, Complement) -> {Leading, Trailing}
        when
            String :: unicode:chardata(),
            Characters :: [grapheme_cluster()],
            Complement :: boolean(),
            Leading :: unicode:chardata(),
            Trailing :: unicode:chardata().

Equivalent to take(String, Characters, Complement, leading)

Link to this function

take(String, Characters, Complement, Dir)

View Source (since OTP 20.0)
-spec take(String, Characters, Complement, Dir) -> {Leading, Trailing}
        when
            String :: unicode:chardata(),
            Characters :: [grapheme_cluster()],
            Complement :: boolean(),
            Dir :: direction(),
            Leading :: unicode:chardata(),
            Trailing :: unicode:chardata().

Takes characters from String as long as the characters are members of set Characters or the complement of set Characters. Dir, which can be leading or trailing, indicates from which direction characters are to be taken.

Example:

5> string:take("abc0z123", lists:seq($a,$z)).
{"abc","0z123"}
6> string:take(<<"abc0z123">>, lists:seq($0,$9), true, leading).
{<<"abc">>,<<"0z123">>}
7> string:take("abc0z123", lists:seq($0,$9), false, trailing).
{"abc0z","123"}
8> string:take(<<"abc0z123">>, lists:seq($a,$z), true, trailing).
{<<"abc0z">>,<<"123">>}
Link to this function

titlecase(String)

View Source (since OTP 20.0)
-spec titlecase(String :: unicode:chardata()) -> unicode:chardata().

Converts String to titlecase.

Example:

1> string:titlecase("ß is a SHARP s").
"Ss is a SHARP s"
-spec to_float(String) -> {Float, Rest} | {error, Reason}
            when
                String :: unicode:chardata(),
                Float :: float(),
                Rest :: unicode:chardata(),
                Reason :: no_float | badarg.

Argument String is expected to start with a valid text represented float (the digits are ASCII values). Remaining characters in the string after the float are returned in Rest.

Example:

1> {F1,Fs} = string:to_float("1.0-1.0e-1"),
1> {F2,[]} = string:to_float(Fs),
1> F1+F2.
0.9
2> string:to_float("3/2=1.5").
{error,no_float}
3> string:to_float("-1.5eX").
{-1.5,"eX"}
Link to this function

to_graphemes(String)

View Source (since OTP 20.0)
-spec to_graphemes(String :: unicode:chardata()) -> [grapheme_cluster()].

Converts String to a list of grapheme clusters.

Example:

1> string:to_graphemes("ß↑e̊").
[223,8593,[101,778]]
2> string:to_graphemes(<<"ß↑e̊"/utf8>>).
[223,8593,[101,778]]
-spec to_integer(String) -> {Int, Rest} | {error, Reason}
              when
                  String :: unicode:chardata(),
                  Int :: integer(),
                  Rest :: unicode:chardata(),
                  Reason :: no_integer | badarg.

Argument String is expected to start with a valid text represented integer (the digits are ASCII values). Remaining characters in the string after the integer are returned in Rest.

Example:

1> {I1,Is} = string:to_integer("33+22"),
1> {I2,[]} = string:to_integer(Is),
1> I1-I2.
11
2> string:to_integer("0.5").
{0,".5"}
3> string:to_integer("x=2").
{error,no_integer}
Link to this function

trim(String)

View Source (since OTP 20.0)
-spec trim(String) -> unicode:chardata() when String :: unicode:chardata().

Equivalent to trim(String, both)

Link to this function

trim(String, Dir)

View Source (since OTP 20.0)
-spec trim(String, Dir) -> unicode:chardata()
        when String :: unicode:chardata(), Dir :: direction() | both.

Equivalent to trim(String, Dir, Whitespace}) where Whitespace is the set of nonbreakable whitespace codepoints, defined as Pattern_White_Space in Unicode Standard Annex #31.

Link to this function

trim(String, Dir, Characters)

View Source (since OTP 20.0)
-spec trim(String, Dir, Characters) -> unicode:chardata()
        when
            String :: unicode:chardata(),
            Dir :: direction() | both,
            Characters :: [grapheme_cluster()].

Returns a string, where leading or trailing, or both, Characters have been removed.

Dir which can be leading, trailing, or both, indicates from which direction characters are to be removed.

Note that [$\r,$\n] is one grapheme cluster according to the Unicode Standard.

Example:

1> string:trim("\t  Hello  \n").
"Hello"
2> string:trim(<<"\t  Hello  \n">>, leading).
<<"Hello  \n">>
3> string:trim(<<".Hello.\n">>, trailing, "\n.").
<<".Hello">>
Link to this function

uppercase(String)

View Source (since OTP 20.0)
-spec uppercase(String :: unicode:chardata()) -> unicode:chardata().

Converts String to uppercase.

See also titlecase/1.

Example:

1> string:uppercase("Michał").
"MICHAŁ"

Obsolete API functions

-spec centre(String, Number) -> Centered
          when String :: string(), Centered :: string(), Number :: non_neg_integer().

Equivalent to centre(String, Number, $ )

Link to this function

centre(String, Number, Character)

View Source
-spec centre(String, Number, Character) -> Centered
          when
              String :: string(),
              Centered :: string(),
              Number :: non_neg_integer(),
              Character :: char().

Returns a string, where String is centered in the string and surrounded by blanks or Character. The resulting string has length Number.

This function is obsolete. Use pad/3.

Link to this function

chars(Character, Number)

View Source
-spec chars(Character, Number) -> String
         when Character :: char(), Number :: non_neg_integer(), String :: string().

Equivalent to chars(Character, Number, [])

Link to this function

chars(Character, Number, Tail)

View Source
-spec chars(Character, Number, Tail) -> String
         when
             Character :: char(),
             Number :: non_neg_integer(),
             Tail :: string(),
             String :: string().

Returns a string consisting of Number characters Character. Optionally, the string can end with string Tail.

This function is obsolete. Use lists:duplicate/2.

-spec chr(String, Character) -> Index
       when String :: string(), Character :: char(), Index :: non_neg_integer().

Returns the index of the first occurrence of Character in String. Returns 0 if Character does not occur.

This function is obsolete. Use find/2.

Link to this function

concat(String1, String2)

View Source
-spec concat(String1, String2) -> String3
          when String1 :: string(), String2 :: string(), String3 :: string().

Concatenates String1 and String2 to form a new string String3, which is returned.

This function is obsolete. Use [String1, String2] as Data argument, and call unicode:characters_to_list/2 or unicode:characters_to_binary/2 to flatten the output.

-spec copies(String, Number) -> Copies
          when String :: string(), Copies :: string(), Number :: non_neg_integer().

Returns a string containing String repeated Number times.

This function is obsolete. Use lists:duplicate/2.

-spec cspan(String, Chars) -> Length
         when String :: string(), Chars :: string(), Length :: non_neg_integer().

Returns the length of the maximum initial segment of String, which consists entirely of characters not from Chars.

This function is obsolete. Use take/3.

Example:

1> string:cspan("\t    abcdef", " \t").
0
Link to this function

join(StringList, Separator)

View Source
-spec join(StringList, Separator) -> String
        when StringList :: [string()], Separator :: string(), String :: string().

Returns a string with the elements of StringList separated by the string in Separator.

This function is obsolete. Use lists:join/2.

Example:

1> join(["one", "two", "three"], ", ").
"one, two, three"
-spec left(String, Number) -> Left
        when String :: string(), Left :: string(), Number :: non_neg_integer().

Equivalent to left(String, Number, $ )

Link to this function

left(String, Number, Character)

View Source
-spec left(String, Number, Character) -> Left
        when
            String :: string(), Left :: string(), Number :: non_neg_integer(), Character :: char().

Returns String with the length adjusted in accordance with Number. The left margin is fixed. If length(String) < Number, then String is padded with blanks or Characters.

This function is obsolete. Use pad/2 or pad/3.

Example:

1> string:left("Hello",10,$.).
"Hello....."
-spec len(String) -> Length when String :: string(), Length :: non_neg_integer().

Returns the number of characters in String.

This function is obsolete. Use length/1.

-spec rchr(String, Character) -> Index
        when String :: string(), Character :: char(), Index :: non_neg_integer().

Returns the index of the last occurrence of Character in String. Returns 0 if Character does not occur.

This function is obsolete. Use find/3.

-spec right(String, Number) -> Right
         when String :: string(), Right :: string(), Number :: non_neg_integer().

Equivalent to right(String, Number, $ )

Link to this function

right(String, Number, Character)

View Source
-spec right(String, Number, Character) -> Right
         when
             String :: string(),
             Right :: string(),
             Number :: non_neg_integer(),
             Character :: char().

Returns String with the length adjusted in accordance with Number. The right margin is fixed. If the length of (String) < Number, then String is padded with blanks or Characters.

This function is obsolete. Use pad/3.

Example:

1> string:right("Hello", 10, $.).
".....Hello"
-spec rstr(String, SubString) -> Index
        when String :: string(), SubString :: string(), Index :: non_neg_integer().

Returns the position where the last occurrence of SubString begins in String. Returns 0 if SubString does not exist in String.

This function is obsolete. Use find/3.

Example:

1> string:rstr(" Hello Hello World World ", "Hello World").
8
-spec span(String, Chars) -> Length
        when String :: string(), Chars :: string(), Length :: non_neg_integer().

Returns the length of the maximum initial segment of String, which consists entirely of characters from Chars.

This function is obsolete. Use take/2.

Example:

1> string:span("\t    abcdef", " \t").
5
-spec str(String, SubString) -> Index
       when String :: string(), SubString :: string(), Index :: non_neg_integer().

Returns the position where the first occurrence of SubString begins in String. Returns 0 if SubString does not exist in String.

This function is obsolete. Use find/2.

Example:

1> string:str(" Hello Hello World World ", "Hello World").
8
-spec strip(string()) -> string().

Equivalent to strip(String, both)

Link to this function

strip(String, Direction)

View Source
-spec strip(String, Direction) -> Stripped
         when String :: string(), Stripped :: string(), Direction :: left | right | both.

Equivalent to strip(String, Direction, $ )

Link to this function

strip(String, Direction, Character)

View Source
-spec strip(String, Direction, Character) -> Stripped
         when
             String :: string(),
             Stripped :: string(),
             Direction :: left | right | both,
             Character :: char().

Returns a string, where leading or trailing, or both, blanks or a number of Character have been removed.

Direction, which can be left, right, or both, indicates from which direction blanks are to be removed. strip/1 is equivalent to strip(String, both).

This function is obsolete. Use trim/3.

Example:

1> string:strip("...Hello.....", both, $.).
"Hello"
Link to this function

sub_string(String, Start)

View Source
-spec sub_string(String, Start) -> SubString
              when String :: string(), SubString :: string(), Start :: pos_integer().

Equivalent to sub_string(String, Start, string:length(String))

Link to this function

sub_string(String, Start, Stop)

View Source
-spec sub_string(String, Start, Stop) -> SubString
              when
                  String :: string(),
                  SubString :: string(),
                  Start :: pos_integer(),
                  Stop :: pos_integer().

Returns a substring of String, starting at position Start to the end of the string, or to and including position Stop.

This function is obsolete. Use slice/3.

Example:

1> sub_string("Hello World", 4, 8).
"lo Wo"
Link to this function

sub_word(String, Number)

View Source
-spec sub_word(String, Number) -> Word when String :: string(), Word :: string(), Number :: integer().

Equivalent to sub_word(String, Number, $ )

Link to this function

sub_word(String, Number, Character)

View Source
-spec sub_word(String, Number, Character) -> Word
            when String :: string(), Word :: string(), Number :: integer(), Character :: char().

Returns the word in position Number of String. Words are separated by blanks or Characters.

This function is obsolete. Use nth_lexeme/3.

Example:

1> string:sub_word(" Hello old boy !",3,$o).
"ld b"
-spec substr(String, Start) -> SubString
          when String :: string(), SubString :: string(), Start :: pos_integer().

Equivalent to substr(String, Start, string:length(String) - Start)

Link to this function

substr(String, Start, Length)

View Source
-spec substr(String, Start, Length) -> SubString
          when
              String :: string(),
              SubString :: string(),
              Start :: pos_integer(),
              Length :: non_neg_integer().

Returns a substring of String, starting at position Start, and ending at the end of the string or at length Length.

This function is obsolete. Use slice/3.

Example:

1> substr("Hello World", 4, 5).
"lo Wo"
-spec to_lower(String) -> Result when String :: io_lib:latin1_string(), Result :: io_lib:latin1_string();
        (Char) -> CharResult when Char :: char(), CharResult :: char().

The specified string or character is case-converted. Notice that the supported character set is ISO/IEC 8859-1 (also called Latin 1); all values outside this set are unchanged.

This function is obsolete use lowercase/1, titlecase/1 or casefold/1.

-spec to_upper(String) -> Result when String :: io_lib:latin1_string(), Result :: io_lib:latin1_string();
        (Char) -> CharResult when Char :: char(), CharResult :: char().

The specified string or character is case-converted. Notice that the supported character set is ISO/IEC 8859-1 (also called Latin 1); all values outside this set are unchanged.

This function is obsolete use uppercase/1, titlecase/1 or casefold/1.

Link to this function

tokens(String, SeparatorList)

View Source
-spec tokens(String, SeparatorList) -> Tokens
          when
              String :: string(),
              SeparatorList :: string(),
              Tokens :: [Token :: nonempty_string()].

Returns a list of tokens in String, separated by the characters in SeparatorList.

Example:

1> tokens("abc defxxghix jkl", "x ").
["abc", "def", "ghi", "jkl"]

Notice that, as shown in this example, two or more adjacent separator characters in String are treated as one. That is, there are no empty strings in the resulting list of tokens.

This function is obsolete. Use lexemes/2.

-spec words(String) -> Count when String :: string(), Count :: pos_integer().

Equivalent to words(String, $ )

Link to this function

words(String, Character)

View Source
-spec words(String, Character) -> Count
         when String :: string(), Character :: char(), Count :: pos_integer().

Returns the number of words in String, separated by blanks or Character.

This function is obsolete. Use lexemes/2.

Example:

1> words(" Hello old boy!", $o).
4