string

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"

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"

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.

By default, IgnoreCase is false and Norm is none.

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

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.

By default, Dir is leading.

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

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

Example:

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

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

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">>]

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"

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>>]

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">>]

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"

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

By default, Char is $\s and Dir is trailing.

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  '

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

Replaces SearchPattern in String with Replacement. Where, default leading, 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">>]

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

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

By default, Length is infinity.

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"

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">>]

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">>}

Converts String to titlecase.

Example:

1> string:titlecase("ß is a SHARP s").
"Ss is a SHARP s"

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:

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

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:

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

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]]

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.

Default Characters is the set of nonbreakable whitespace codepoints, defined as Pattern_White_Space in Unicode Standard Annex #31. By default, Dir is both.

Notice 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">>

Converts String to uppercase.

See also titlecase/1.

Example:

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

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.

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

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

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.

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.

Returns a string containing String repeated Number times.

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

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:

> string:cspan("\t    abcdef", " \t").
0

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

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

Example:

> join(["one", "two", "three"], ", ").
"one, two, three"

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:

> string:left("Hello",10,$.).
"Hello....."

Returns the number of characters in String.

This function is obsolete. Use length/1.

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.

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:

> string:right("Hello", 10, $.).
".....Hello"

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:

> string:rstr(" Hello Hello World World ", "Hello World").
8

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:

> string:span("\t    abcdef", " \t").
5

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:

> string:str(" Hello Hello World World ", "Hello World").
8

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:

> string:strip("...Hello.....", both, $.).
"Hello"

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:

sub_string("Hello World", 4, 8).
"lo Wo"

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:

> substr("Hello World", 4, 5).
"lo Wo"

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

This function is obsolete. Use nth_lexeme/3.

Example:

> string:sub_word(" Hello old boy !",3,$o).
"ld b"

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, uppercase/1, titlecase/1 or casefold/1.

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

Example:

> 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.

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

This function is obsolete. Use lexemes/2.

Example:

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