string(3)

MODULE
string - String Processing Functions

DESCRIPTION

This module contains functions for string processing.

EXPORTS

len(String) -> Length

    Types
        String = string()
        Length = integer()

    Returns the number of characters in the string.

equal(String1, String2) -> bool()

    Types
        String1 = String2 = string()

    Tests whether two strings are equal. Returns true if they are, otherwise false.

concat(String1, String2) -> String3

    Types
        String1 = String2 = String3 = string()

    Concatenates two strings to form a new string. Returns the new string.

chr(String, Character) -> Index
rchr(String, Character) -> Index

    Types
        String = string()
        Character = char()
        Index = integer()

    Returns the index of the first/last occurrence of Character in String. 0 is returned if Character does not occur.

str(String, SubString) -> Index
rstr(String, SubString) -> Index

    Types
        String = SubString = string()
        Index = integer()

    Returns the position where the first/last occurrence of SubString begins in String. 0 is returned if SubString does not exist in String. For example:
    > string:str(" Hello Hello World World ", "Hello World").
    8

span(String, Chars) -> Length
cspan(String, Chars) -> Length

    Types
        String = Chars = string()
        Length = integer()

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

    For example:
    > string:span("\t    abcdef", " \t").
    5
    > string:cspan("\t    abcdef", " \t").
    0

substr(String, Start) -> SubString
substr(String, Start, Length) -> Substring

    Types
        String = SubString = string()
        Start = Length = integer()

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

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

tokens(String, SeparatorList) -> Tokens

    Types
        String = SeparatorList = string()
        Tokens = [string()]

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

    For example:
    > tokens("abc defxxghix jkl", "x ").
    ["abc", "def", "ghi", "jkl"]

chars(Character, Number) -> String
chars(Character, Number, Tail) -> String

    Types
        Character = char()
        Number = integer()
        String = string()

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

copies(String, Number) -> Copies

    Types
        String = Copies = string()
        Number = integer()

    Returns a string containing String repeated Number times.

words(String) -> Count
words(String, Character) -> Count

    Types
        String = string()
        Character = char()
        Count = integer()

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

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

sub_word(String, Number) -> Word
sub_word(String, Number, Character) -> Word

    Types
        String = Word = string()
        Character = char()
        Number = integer()

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

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

strip(String) -> Stripped
strip(String, Direction) -> Stripped
strip(String, Direction, Character) -> Stripped

    Types
        String = Stripped = string()
        Direction = left | right | both
        Character = char()

    Returns a string, where leading and/or trailing blanks or a number of Character have been removed. Direction can be left, right, or both and indicates from which direction blanks are to be removed. The function strip/1 is equivalent to strip(String, both).

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

left(String, Number) -> Left
left(String, Number, Character) -> Left

    Types
        String = Left = string()
        Character = char
        Number = integer()

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

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

right(String, Number) -> Right
right(String, Number, Character) -> Right

    Types
        String = Right = string()
        Character = char
        Number = integer()

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

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

centre(String, Number) -> Centered
centre(String, Number, Character) -> Centered

    Types
        String = Centered = string()
        Character = char
        Number = integer()

    Returns a string, where String is centred in the string and surrounded by blanks or characters. The resulting string will have the length Number.

sub_string(String, Start) -> SubString
sub_string(String, Start, Stop) -> SubString

    Types
        String = SubString = string()
        Start = Stop = integer()

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

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

to_float(String) -> {Float,Rest} | {error,Reason}

    Types
        String = string()
        Float = float()
        Rest = string()
        Reason = no_float | not_a_list

    Argument String is expected to start with a valid text represented float (the digits being 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.
              0.900000
              > string:to_float("3/2=1.5").
              {error,no_float}
              > string:to_float("-1.5eX").
              {-1.50000,"eX"}

to_integer(String) -> {Int,Rest} | {error,Reason}

    Types
        String = string()
        Int = integer()
        Rest = string()
        Reason = no_integer | not_a_list

    Argument String is expected to start with a valid text represented integer (the digits being 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}

Notes

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

The regular expression functions have been moved to their own module regexp (see regexp(3)). The old entry points still exist for backwards compatibility, but will be removed in a future release so that users are encouraged to use the module regexp.

  Note:

Any undocumented functions in string should not be used.

AUTHORS
Robert Virding - support@erlang.ericsson.se
Torbjorn Tornkvist - support@erlang.ericsson.se