<?xml version="1.0" encoding="latin1" ?>
<!DOCTYPE erlref SYSTEM "erlref.dtd">
<erlref>
<header>
<copyright>
<year>1996</year><year>2009</year>
<holder>Ericsson AB. All Rights Reserved.</holder>
</copyright>
<legalnotice>
The contents of this file are subject to the Erlang Public License,
Version 1.1, (the "License"); you may not use this file except in
compliance with the License. You should have received a copy of the
Erlang Public License along with this software. If not, it can be
retrieved online at http://www.erlang.org/.
Software distributed under the License is distributed on an "AS IS"
basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
the License for the specific language governing rights and limitations
under the License.
</legalnotice>
<title>string</title>
<prepared>Robert Virding</prepared>
<responsible>Bjarne Dacker</responsible>
<docno>1</docno>
<approved>Bjarne Däcker</approved>
<checked></checked>
<date>96-09-28</date>
<rev>A</rev>
<file>string.sgml</file>
</header>
<module>string</module>
<modulesummary>String Processing Functions</modulesummary>
<description>
<p>This module contains functions for string processing.</p>
</description>
<funcs>
<func>
<name>len(String) -> Length</name>
<fsummary>Return the length of a string</fsummary>
<type>
<v>String = string()</v>
<v>Length = integer()</v>
</type>
<desc>
<p>Returns the number of characters in the string.</p>
</desc>
</func>
<func>
<name>equal(String1, String2) -> bool()</name>
<fsummary>Test string equality</fsummary>
<type>
<v>String1 = String2 = string()</v>
</type>
<desc>
<p>Tests whether two strings are equal. Returns <c>true</c> if
they are, otherwise <c>false</c>.</p>
</desc>
</func>
<func>
<name>concat(String1, String2) -> String3</name>
<fsummary>Concatenate two strings</fsummary>
<type>
<v>String1 = String2 = String3 = string()</v>
</type>
<desc>
<p>Concatenates two strings to form a new string. Returns the
new string.</p>
</desc>
</func>
<func>
<name>chr(String, Character) -> Index</name>
<name>rchr(String, Character) -> Index</name>
<fsummary>Return the index of the first/last occurrence of<c>Character</c>in <c>String</c></fsummary>
<type>
<v>String = string()</v>
<v>Character = char()</v>
<v>Index = integer()</v>
</type>
<desc>
<p>Returns the index of the first/last occurrence of
<c>Character</c> in <c>String</c>. <c>0</c> is returned if <c>Character</c> does not
occur.</p>
</desc>
</func>
<func>
<name>str(String, SubString) -> Index</name>
<name>rstr(String, SubString) -> Index</name>
<fsummary>Find the index of a substring</fsummary>
<type>
<v>String = SubString = string()</v>
<v>Index = integer()</v>
</type>
<desc>
<p>Returns the position where the first/last occurrence of
<c>SubString</c> begins in <c>String</c>. <c>0</c> is returned if <c>SubString</c>
does not exist in <c>String</c>.
For example:</p>
<code type="none">
> string:str(" Hello Hello World World ", "Hello World").
8 </code>
</desc>
</func>
<func>
<name>span(String, Chars) -> Length </name>
<name>cspan(String, Chars) -> Length</name>
<fsummary>Span characters at start of string</fsummary>
<type>
<v>String = Chars = string()</v>
<v>Length = integer()</v>
</type>
<desc>
<p>Returns the length of the maximum initial segment of
String, which consists entirely of characters from (not
from) Chars.</p>
<p>For example:</p>
<code type="none">
> string:span("\\t abcdef", " \\t").
5
> string:cspan("\\t abcdef", " \\t").
0 </code>
</desc>
</func>
<func>
<name>substr(String, Start) -> SubString</name>
<name>substr(String, Start, Length) -> Substring</name>
<fsummary>Return a substring of <c>String</c></fsummary>
<type>
<v>String = SubString = string()</v>
<v>Start = Length = integer()</v>
</type>
<desc>
<p>Returns a substring of <c>String</c>, starting at the
position <c>Start</c>, and ending at the end of the string or
at length <c>Length</c>.</p>
<p>For example:</p>
<code type="none">
> substr("Hello World", 4, 5).
"lo Wo" </code>
</desc>
</func>
<func>
<name>tokens(String, SeparatorList) -> Tokens</name>
<fsummary>Split string into tokens</fsummary>
<type>
<v>String = SeparatorList = string()</v>
<v>Tokens = [string()]</v>
</type>
<desc>
<p>Returns a list of tokens in <c>String</c>, separated by the
characters in <c>SeparatorList</c>.</p>
<p>For example:</p>
<code type="none">
> tokens("abc defxxghix jkl", "x ").
["abc", "def", "ghi", "jkl"] </code>
</desc>
</func>
<func>
<name>join(StringList, Separator) -> String</name>
<fsummary>Join a list of strings with separator</fsummary>
<type>
<v>StringList = [string()]</v>
<v>Separator = string()</v>
</type>
<desc>
<p>Returns a string with the elements of <c>StringList</c>
separated by the string in <c>Seperator</c>.</p>
<p>For example:</p>
<code type="none">
> join(["one", "two", "three"], ", ").
"one, two, three" </code>
</desc>
</func>
<func>
<name>chars(Character, Number) -> String</name>
<name>chars(Character, Number, Tail) -> String</name>
<fsummary>Returns a string consisting of numbers of characters</fsummary>
<type>
<v>Character = char()</v>
<v>Number = integer()</v>
<v>String = string()</v>
</type>
<desc>
<p>Returns a string consisting of <c>Number</c> of characters
<c>Character</c>. Optionally, the string can end with the
string <c>Tail</c>.</p>
</desc>
</func>
<func>
<name>copies(String, Number) -> Copies</name>
<fsummary>Copy a string</fsummary>
<type>
<v>String = Copies = string()</v>
<v>Number = integer()</v>
</type>
<desc>
<p>Returns a string containing <c>String</c> repeated
<c>Number</c> times.</p>
</desc>
</func>
<func>
<name>words(String) -> Count</name>
<name>words(String, Character) -> Count</name>
<fsummary>Count blank separated words</fsummary>
<type>
<v>String = string()</v>
<v>Character = char()</v>
<v>Count = integer()</v>
</type>
<desc>
<p>Returns the number of words in <c>String</c>, separated by
blanks or <c>Character</c>.</p>
<p>For example:</p>
<code type="none">
> words(" Hello old boy!", $o).
4 </code>
</desc>
</func>
<func>
<name>sub_word(String, Number) -> Word</name>
<name>sub_word(String, Number, Character) -> Word</name>
<fsummary>Extract subword</fsummary>
<type>
<v>String = Word = string()</v>
<v>Character = char()</v>
<v>Number = integer()</v>
</type>
<desc>
<p>Returns the word in position <c>Number</c> of <c>String</c>.
Words are separated by blanks or <c>Character</c>s.</p>
<p>For example:</p>
<code type="none">
> string:sub_word(" Hello old boy !",3,$o).
"ld b" </code>
</desc>
</func>
<func>
<name>strip(String) -> Stripped</name>
<name>strip(String, Direction) -> Stripped</name>
<name>strip(String, Direction, Character) -> Stripped</name>
<fsummary>Strip leading or trailing characters</fsummary>
<type>
<v>String = Stripped = string()</v>
<v>Direction = left | right | both</v>
<v>Character = char()</v>
</type>
<desc>
<p>Returns a string, where leading and/or trailing blanks or a
number of <c>Character</c> have been removed.
<c>Direction</c> can be <c>left</c>, <c>right</c>, or
<c>both</c> and indicates from which direction blanks are to be
removed. The function <c>strip/1</c> is equivalent to
<c>strip(String, both)</c>.</p>
<p>For example:</p>
<code type="none">
> string:strip("...Hello.....", both, $.).
"Hello" </code>
</desc>
</func>
<func>
<name>left(String, Number) -> Left</name>
<name>left(String, Number, Character) -> Left</name>
<fsummary>Adjust left end of string</fsummary>
<type>
<v>String = Left = string()</v>
<v>Character = char</v>
<v>Number = integer()</v>
</type>
<desc>
<p>Returns the <c>String</c> with the length adjusted in
accordance with <c>Number</c>. The left margin is
fixed. If the <c>length(String)</c> < <c>Number</c>,
<c>String</c> is padded with blanks or <c>Character</c>s.</p>
<p>For example:</p>
<code type="none">
> string:left("Hello",10,$.).
"Hello....." </code>
</desc>
</func>
<func>
<name>right(String, Number) -> Right</name>
<name>right(String, Number, Character) -> Right</name>
<fsummary>Adjust right end of string</fsummary>
<type>
<v>String = Right = string()</v>
<v>Character = char</v>
<v>Number = integer()</v>
</type>
<desc>
<p>Returns the <c>String</c> with the length adjusted in
accordance with <c>Number</c>. The right margin is
fixed. If the length of <c>(String)</c> < <c>Number</c>,
<c>String</c> is padded with blanks or <c>Character</c>s.</p>
<p>For example:</p>
<code type="none">
> string:right("Hello", 10, $.).
".....Hello" </code>
</desc>
</func>
<func>
<name>centre(String, Number) -> Centered</name>
<name>centre(String, Number, Character) -> Centered</name>
<fsummary>Center a string</fsummary>
<type>
<v>String = Centered = string()</v>
<v>Character = char</v>
<v>Number = integer()</v>
</type>
<desc>
<p>Returns a string, where <c>String</c> is centred in the
string and surrounded by blanks or characters. The resulting
string will have the length <c>Number</c>.</p>
</desc>
</func>
<func>
<name>sub_string(String, Start) -> SubString</name>
<name>sub_string(String, Start, Stop) -> SubString</name>
<fsummary>Extract a substring</fsummary>
<type>
<v>String = SubString = string()</v>
<v>Start = Stop = integer()</v>
</type>
<desc>
<p>Returns a substring of <c>String</c>, starting at the
position <c>Start</c> to the end of the string, or to and
including the <c>Stop</c> position.</p>
<p>For example:</p>
<code type="none">
sub_string("Hello World", 4, 8).
"lo Wo" </code>
</desc>
</func>
<func>
<name>to_float(String) -> {Float,Rest} | {error,Reason} </name>
<fsummary>Returns a float whose text representation is the integers (ASCII values) in String.</fsummary>
<type>
<v>String = string()</v>
<v>Float = float()</v>
<v>Rest = string()</v>
<v>Reason = no_float | not_a_list</v>
</type>
<desc>
<p>Argument <c>String</c> 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 <c>Rest</c>.</p>
<p>Example:</p>
<code type="none">
> {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"}</code>
</desc>
</func>
<func>
<name>to_integer(String) -> {Int,Rest} | {error,Reason} </name>
<fsummary>Returns an integer whose text representation is the integers (ASCII values) in String.</fsummary>
<type>
<v>String = string()</v>
<v>Int = integer()</v>
<v>Rest = string()</v>
<v>Reason = no_integer | not_a_list</v>
</type>
<desc>
<p>Argument <c>String</c> 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 <c>Rest</c>.</p>
<p>Example:</p>
<code type="none">
> {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}</code>
</desc>
</func>
<func>
<name>to_lower(String) -> Result</name>
<name>to_lower(Char) -> CharResult</name>
<name>to_upper(String) -> Result</name>
<name>to_upper(Char) -> CharResult</name>
<fsummary>Convert case of string (ISO/IEC 8859-1)</fsummary>
<type>
<v>String = Result = string()</v>
<v>Char = CharResult = integer()</v>
</type>
<desc>
<p>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</p>
</desc>
</func>
</funcs>
<section>
<title>Notes</title>
<p>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.
</p>
<note>
<p>Any undocumented functions in <c>string</c> should not be used.</p>
</note>
</section>
</erlref>
