<?xml version="1.0" encoding="latin1" ?> <!DOCTYPE erlref SYSTEM "erlref.dtd"> <erlref> <header> <copyright> <year>1996</year><year>2011</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 name="len" arity="1"/> <fsummary>Return the length of a string</fsummary> <desc> <p>Returns the number of characters in the string.</p> </desc> </func> <func> <name name="equal" arity="2"/> <fsummary>Test string equality</fsummary> <desc> <p>Tests whether two strings are equal. Returns <c>true</c> if they are, otherwise <c>false</c>.</p> </desc> </func> <func> <name name="concat" arity="2"/> <fsummary>Concatenate two strings</fsummary> <desc> <p>Concatenates two strings to form a new string. Returns the new string.</p> </desc> </func> <func> <name name="chr" arity="2"/> <name name="rchr" arity="2"/> <fsummary>Return the index of the first/last occurrence of<c>Character</c>in <c>String</c></fsummary> <desc> <p>Returns the index of the first/last occurrence of <c><anno>Character</anno></c> in <c><anno>String</anno></c>. <c>0</c> is returned if <c><anno>Character</anno></c> does not occur.</p> </desc> </func> <func> <name name="str" arity="2"/> <name name="rstr" arity="2"/> <fsummary>Find the index of a substring</fsummary> <desc> <p>Returns the position where the first/last occurrence of <c><anno>SubString</anno></c> begins in <c><anno>String</anno></c>. <c>0</c> is returned if <c><anno>SubString</anno></c> does not exist in <c><anno>String</anno></c>. For example:</p> <code type="none"> > string:str(" Hello Hello World World ", "Hello World"). 8 </code> </desc> </func> <func> <name name="span" arity="2"/> <name name="cspan" arity="2"/> <fsummary>Span characters at start of string</fsummary> <desc> <p>Returns the length of the maximum initial segment of <c><anno>String</anno></c>, which consists entirely of characters from (not from) <c><anno>Chars</anno></c>.</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 name="substr" arity="2"/> <name name="substr" arity="3"/> <fsummary>Return a substring of <c>String</c></fsummary> <desc> <p>Returns a substring of <c><anno>String</anno></c>, starting at the position <c><anno>Start</anno></c>, and ending at the end of the string or at length <c><anno>Length</anno></c>.</p> <p>For example:</p> <code type="none"> > substr("Hello World", 4, 5). "lo Wo" </code> </desc> </func> <func> <name name="tokens" arity="2"/> <fsummary>Split string into tokens</fsummary> <desc> <p>Returns a list of tokens in <c><anno>String</anno></c>, separated by the characters in <c><anno>SeparatorList</anno></c>.</p> <p>For example:</p> <code type="none"> > tokens("abc defxxghix jkl", "x "). ["abc", "def", "ghi", "jkl"] </code> </desc> </func> <func> <name name="join" arity="2"/> <fsummary>Join a list of strings with separator</fsummary> <desc> <p>Returns a string with the elements of <c><anno>StringList</anno></c> separated by the string in <c><anno>Separator</anno></c>.</p> <p>For example:</p> <code type="none"> > join(["one", "two", "three"], ", "). "one, two, three" </code> </desc> </func> <func> <name name="chars" arity="2"/> <name name="chars" arity="3"/> <fsummary>Returns a string consisting of numbers of characters</fsummary> <desc> <p>Returns a string consisting of <c><anno>Number</anno></c> of characters <c><anno>Character</anno></c>. Optionally, the string can end with the string <c><anno>Tail</anno></c>.</p> </desc> </func> <func> <name name="copies" arity="2"/> <fsummary>Copy a string</fsummary> <desc> <p>Returns a string containing <c><anno>String</anno></c> repeated <c><anno>Number</anno></c> times.</p> </desc> </func> <func> <name name="words" arity="1"/> <name name="words" arity="2"/> <fsummary>Count blank separated words</fsummary> <desc> <p>Returns the number of words in <c><anno>String</anno></c>, separated by blanks or <c><anno>Character</anno></c>.</p> <p>For example:</p> <code type="none"> > words(" Hello old boy!", $o). 4 </code> </desc> </func> <func> <name name="sub_word" arity="2"/> <name name="sub_word" arity="3"/> <fsummary>Extract subword</fsummary> <desc> <p>Returns the word in position <c><anno>Number</anno></c> of <c><anno>String</anno></c>. Words are separated by blanks or <c><anno>Character</anno></c>s.</p> <p>For example:</p> <code type="none"> > string:sub_word(" Hello old boy !",3,$o). "ld b" </code> </desc> </func> <func> <name name="strip" arity="1"/> <name name="strip" arity="2"/> <name name="strip" arity="3"/> <fsummary>Strip leading or trailing characters</fsummary> <desc> <p>Returns a string, where leading and/or trailing blanks or a number of <c><anno>Character</anno></c> have been removed. <c><anno>Direction</anno></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, $.). "Hello" </code> </desc> </func> <func> <name name="left" arity="2"/> <name name="left" arity="3"/> <fsummary>Adjust left end of string</fsummary> <desc> <p>Returns the <c><anno>String</anno></c> with the length adjusted in accordance with <c><anno>Number</anno></c>. The left margin is fixed. If the <c>length(<anno>String</anno>)</c> < <c><anno>Number</anno></c>, <c><anno>String</anno></c> is padded with blanks or <c><anno>Character</anno></c>s.</p> <p>For example:</p> <code type="none"> > string:left("Hello",10,$.). "Hello....." </code> </desc> </func> <func> <name name="right" arity="2"/> <name name="right" arity="3"/> <fsummary>Adjust right end of string</fsummary> <desc> <p>Returns the <c><anno>String</anno></c> with the length adjusted in accordance with <c><anno>Number</anno></c>. The right margin is fixed. If the length of <c>(<anno>String</anno>)</c> < <c><anno>Number</anno></c>, <c><anno>String</anno></c> is padded with blanks or <c><anno>Character</anno></c>s.</p> <p>For example:</p> <code type="none"> > string:right("Hello", 10, $.). ".....Hello" </code> </desc> </func> <func> <name name="centre" arity="2"/> <name name="centre" arity="3"/> <fsummary>Center a string</fsummary> <desc> <p>Returns a string, where <c><anno>String</anno></c> is centred in the string and surrounded by blanks or characters. The resulting string will have the length <c><anno>Number</anno></c>.</p> </desc> </func> <func> <name name="sub_string" arity="2"/> <name name="sub_string" arity="3"/> <fsummary>Extract a substring</fsummary> <desc> <p>Returns a substring of <c><anno>String</anno></c>, starting at the position <c><anno>Start</anno></c> to the end of the string, or to and including the <c><anno>Stop</anno></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 name="to_lower" arity="1" clause_i="1"/> <name name="to_lower" arity="1" clause_i="2"/> <name name="to_upper" arity="1" clause_i="1"/> <name name="to_upper" arity="1" clause_i="2"/> <fsummary>Convert case of string (ISO/IEC 8859-1)</fsummary> <type variable="String" name_i="1"/> <type variable="Result" name_i="1"/> <type variable="Char"/> <type variable="CharResult"/> <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>