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<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<refentry xml:id="function.substr-compare" xmlns="http://docbook.org/ns/docbook">
<refnamediv>
<refname>substr_compare</refname>
<refpurpose>Binary safe comparison of two strings from an offset, up to length characters</refpurpose>
</refnamediv>
<refsect1 role="description">
&reftitle.description;
<methodsynopsis>
<type>int</type><methodname>substr_compare</methodname>
<methodparam><type>string</type><parameter>haystack</parameter></methodparam>
<methodparam><type>string</type><parameter>needle</parameter></methodparam>
<methodparam><type>int</type><parameter>offset</parameter></methodparam>
<methodparam choice="opt"><type class="union"><type>int</type><type>null</type></type><parameter>length</parameter><initializer>&null;</initializer></methodparam>
<methodparam choice="opt"><type>bool</type><parameter>case_insensitive</parameter><initializer>&false;</initializer></methodparam>
</methodsynopsis>
<para>
<function>substr_compare</function> compares <parameter>haystack</parameter>
from position <parameter>offset</parameter> with <parameter>needle</parameter>
up to <parameter>length</parameter> characters.
</para>
</refsect1>
<refsect1 role="parameters">
&reftitle.parameters;
<para>
<variablelist>
<varlistentry>
<term><parameter>haystack</parameter></term>
<listitem>
<para>
The main string being compared.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>needle</parameter></term>
<listitem>
<para>
The secondary string being compared.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>offset</parameter></term>
<listitem>
<para>
The start position for the comparison. If negative, it starts counting
from the end of the string.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>length</parameter></term>
<listitem>
<para>
The length of the comparison. The default value is the largest of the
length of the <parameter>needle</parameter> compared to the length of
<parameter>haystack</parameter> minus the
<parameter>offset</parameter>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>case_insensitive</parameter></term>
<listitem>
<para>
If <parameter>case_insensitive</parameter> is &true;, comparison is
case insensitive.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect1>
<refsect1 role="returnvalues">
&reftitle.returnvalues;
<para>
Returns <literal>-1</literal> if <parameter>haystack</parameter> from position
<parameter>offset</parameter> is less than <parameter>needle</parameter>, <literal>1</literal>
if it is greater than <parameter>needle</parameter>, and <literal>0</literal> if they are equal.
If <parameter>offset</parameter> is equal to (prior to PHP 7.2.18, 7.3.5) or
greater than the length of <parameter>haystack</parameter>, or the
<parameter>length</parameter> is set and is less than 0,
<function>substr_compare</function> prints a warning and returns
&false;.
</para>
</refsect1>
<refsect1 role="changelog">
&reftitle.changelog;
<para>
<informaltable>
<tgroup cols="2">
<thead>
<row>
<entry>&Version;</entry>
<entry>&Description;</entry>
</row>
</thead>
<tbody>
&standard.changelog.binary-safe-string-comparison;
<row>
<entry>8.0.0</entry>
<entry>
<parameter>length</parameter> is nullable now.
</entry>
</row>
<row>
<entry>7.2.18, 7.3.5</entry>
<entry>
<parameter>offset</parameter> may now be equal to the length of <parameter>haystack</parameter>.
</entry>
</row>
</tbody>
</tgroup>
</informaltable>
</para>
</refsect1>
<refsect1 role="examples">
&reftitle.examples;
<para>
<example>
<title>A <function>substr_compare</function> example</title>
<programlisting role="php">
<![CDATA[
<?php
echo substr_compare("abcde", "bc", 1, 2); // 0
echo substr_compare("abcde", "de", -2, 2); // 0
echo substr_compare("abcde", "bcg", 1, 2); // 0
echo substr_compare("abcde", "BC", 1, 2, true); // 0
echo substr_compare("abcde", "bc", 1, 3); // 1
echo substr_compare("abcde", "cd", 1, 2); // -1
echo substr_compare("abcde", "abc", 5, 1); // warning
?>
]]>
</programlisting>
</example>
</para>
</refsect1>
<refsect1 role="seealso">
&reftitle.seealso;
<para>
<simplelist>
<member><function>strncmp</function></member>
</simplelist>
</para>
</refsect1>
</refentry>
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