string

MODULE

string

MODULE SUMMARY

String Processing Functions

DESCRIPTION

This module contains functions for string processing.

EXPORTS

len(String) -> Length

Types:

String = string()

Length = integer() >= 0

Returns the number of characters in the string.

equal(String1, String2) -> boolean()

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() >= 0

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() >= 0

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() >= 0

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 = integer() >= 1

Length = integer() >= 0

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 = [Token :: nonempty_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"]

Note that, as shown in the example above, two or more adjacent separator characters in String will be treated as one. That is, there will not be any empty strings in the resulting list of tokens.

join(StringList, Separator) -> String

Types:

StringList = [string()]

Separator = String = string()

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

For example:

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

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

Types:

Character = char()

Number = integer() >= 0

Tail = 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() >= 0

Returns a string containing String repeated Number times.

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

Types:

String = string()

Character = char()

Count = integer() >= 1

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()

Number = integer()

Character = char()

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 :: string()) -> string()
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()

Number = integer() >= 0

Character = char()

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()

Number = integer() >= 0

Character = char()

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()

Number = integer() >= 0

Character = char()

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() >= 1

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.
          0.9
          > string:to_float("3/2=1.5").
          {error,no_float}
          > string:to_float("-1.5eX").
          {-1.5,"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}

to_lower(String) -> Result
to_lower(Char) -> CharResult
to_upper(String) -> Result
to_upper(Char) -> CharResult

Types:

String = Result = io_lib:latin1_string()

Char = CharResult = char()

The given string or character is case-converted. Note that the supported character set is ISO/IEC 8859-1 (a.k.a. Latin 1), all values outside this set is unchanged

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.

Note

Any undocumented functions in string should not be used.