string - String Processing Functions

This module contains functions for string processing.

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}

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:

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