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<?xml version="1.0" encoding="iso-8859-1"?>
<!-- $Revision: 1.11 $ -->
<!-- splitted from ./en/functions/strings.xml, last change in rev 1.2 -->
<refentry id="function.substr">
<refnamediv>
<refname>substr</refname>
<refpurpose>Return part of a string</refpurpose>
</refnamediv>
<refsect1>
<title>Description</title>
<methodsynopsis>
<type>string</type><methodname>substr</methodname>
<methodparam><type>string</type><parameter>string</parameter></methodparam>
<methodparam><type>int</type><parameter>start</parameter></methodparam>
<methodparam choice="opt"><type>int</type><parameter>length</parameter></methodparam>
</methodsynopsis>
<para>
<function>substr</function> returns the portion of <parameter>string</parameter>
specified by the <parameter>start</parameter> and
<parameter>length</parameter> parameters.
</para>
<para>
If <parameter>start</parameter> is non-negative, the returned string
will start at the <parameter>start</parameter>'th position in
<parameter>string</parameter>, counting from zero. For instance,
in the string '<literal>abcdef</literal>', the character at
position <literal>0</literal> is '<literal>a</literal>', the
character at position <literal>2</literal> is
'<literal>c</literal>', and so forth.
</para>
<example>
<title>Basic <function>substr</function> usage</title>
<programlisting role="php">
<![CDATA[
<?php
echo substr('abcdef', 1); // bcdef
echo substr('abcdef', 1, 3); // bcd
echo substr('abcdef', 0, 4); // abcd
echo substr('abcdef', 0, 8); // abcdef
echo substr('abcdef', -1, 1); // f
// Accessing single characters in a string
// can also be achived using "curly braces"
$string = 'abcdef';
echo $string{0}; // a
echo $string{3}; // d
echo $string{strlen($string)-1}; // f
?>
]]>
</programlisting>
</example>
<para>
If <parameter>start</parameter> is negative, the returned string
will start at the <parameter>start</parameter>'th character
from the end of <parameter>string</parameter>.
</para>
<example>
<title>Using a negative <parameter>start</parameter></title>
<programlisting role="php">
<![CDATA[
<?php
$rest = substr("abcdef", -1); // returns "f"
$rest = substr("abcdef", -2); // returns "ef"
$rest = substr("abcdef", -3, 1); // returns "d"
?>
]]>
</programlisting>
</example>
<para>
If <parameter>length</parameter> is given and is positive, the string
returned will contain at most <parameter>length</parameter> characters
beginning from <parameter>start</parameter> (depending on the length of
<parameter>string</parameter>). If <parameter>string</parameter> is less
than or equal to <parameter>start</parameter> characters long, &false;
will be returned.
</para>
<para>
If <parameter>length</parameter> is given and is negative, then that many
characters will be omitted from the end of <parameter>string</parameter>
(after the start position has been calculated when a
<parameter>start</parameter> is negative). If
<parameter>start</parameter> denotes a position beyond this truncation,
an empty string will be returned.
</para>
<example>
<title>Using a negative <parameter>length</parameter></title>
<programlisting role="php">
<![CDATA[
<?php
$rest = substr("abcdef", 0, -1); // returns "abcde"
$rest = substr("abcdef", 2, -1); // returns "cde"
$rest = substr("abcdef", 4, -4); // returns ""
$rest = substr("abcdef", -3, -1); // returns "de"
?>
]]>
</programlisting>
</example>
<para>
See also <function>strrchr</function>,
<function>substr_replace</function>,
<function>ereg</function>,
<function>trim</function>,
<function>mb_substr</function> and
<function>wordwrap</function>.
</para>
</refsect1>
</refentry>
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