<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <title>Perform a regular expression match</title> </head> <body><div class="manualnavbar" style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.preg-match-all.html">preg_match_all</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.preg-quote.html">preg_quote</a></div> <div class="up"><a href="ref.pcre.html">PCRE Functions</a></div> <div class="home"><a href="index.html">PHP Manual</a></div> </div><hr /><div id="function.preg-match" class="refentry"> <div class="refnamediv"> <h1 class="refname">preg_match</h1> <p class="verinfo">(PHP 4, PHP 5, PHP 7)</p><p class="refpurpose"><span class="refname">preg_match</span> — <span class="dc-title">Perform a regular expression match</span></p> </div> <div class="refsect1 description" id="refsect1-function.preg-match-description"> <h3 class="title">Description</h3> <div class="methodsynopsis dc-description"> <span class="type">int</span> <span class="methodname"><strong>preg_match</strong></span> ( <span class="methodparam"><span class="type">string</span> <code class="parameter">$pattern</code></span> , <span class="methodparam"><span class="type">string</span> <code class="parameter">$subject</code></span> [, <span class="methodparam"><span class="type">array</span> <code class="parameter reference">&$matches</code></span> [, <span class="methodparam"><span class="type">int</span> <code class="parameter">$flags</code><span class="initializer"> = 0</span></span> [, <span class="methodparam"><span class="type">int</span> <code class="parameter">$offset</code><span class="initializer"> = 0</span></span> ]]] )</div> <p class="para rdfs-comment"> Searches <code class="parameter">subject</code> for a match to the regular expression given in <code class="parameter">pattern</code>. </p> </div> <div class="refsect1 parameters" id="refsect1-function.preg-match-parameters"> <h3 class="title">Parameters</h3> <p class="para"> <dl> <dt> <code class="parameter">pattern</code></dt> <dd> <p class="para"> The pattern to search for, as a string. </p> </dd> <dt> <code class="parameter">subject</code></dt> <dd> <p class="para"> The input string. </p> </dd> <dt> <code class="parameter">matches</code></dt> <dd> <p class="para"> If <code class="parameter">matches</code> is provided, then it is filled with the results of search. <var class="varname"><var class="varname">$matches[0]</var></var> will contain the text that matched the full pattern, <var class="varname"><var class="varname">$matches[1]</var></var> will have the text that matched the first captured parenthesized subpattern, and so on. </p> </dd> <dt> <code class="parameter">flags</code></dt> <dd> <p class="para"> <code class="parameter">flags</code> can be a combination of the following flags: <dl> <dt> <strong><code>PREG_OFFSET_CAPTURE</code></strong></dt> <dd> <p class="para"> If this flag is passed, for every occurring match the appendant string offset will also be returned. Note that this changes the value of <code class="parameter">matches</code> into an array where every element is an array consisting of the matched string at offset <em>0</em> and its string offset into <code class="parameter">subject</code> at offset <em>1</em>. <div class="informalexample"> <div class="example-contents"> <div class="phpcode"><code><span style="color: #000000"> <span style="color: #0000BB"><?php<br />preg_match</span><span style="color: #007700">(</span><span style="color: #DD0000">'/(foo)(bar)(baz)/'</span><span style="color: #007700">, </span><span style="color: #DD0000">'foobarbaz'</span><span style="color: #007700">, </span><span style="color: #0000BB">$matches</span><span style="color: #007700">, </span><span style="color: #0000BB">PREG_OFFSET_CAPTURE</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$matches</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span> </span> </code></div> </div> <p class="para">The above example will output:</p> <div class="example-contents screen"> <div class="cdata"><pre> Array ( [0] => Array ( [0] => foobarbaz [1] => 0 ) [1] => Array ( [0] => foo [1] => 0 ) [2] => Array ( [0] => bar [1] => 3 ) [3] => Array ( [0] => baz [1] => 6 ) ) </pre></div> </div> </div> </p> </dd> <dt> <strong><code>PREG_UNMATCHED_AS_NULL</code></strong></dt> <dd> <p class="para"> If this flag is passed, unmatched subpatterns are reported as <strong><code>NULL</code></strong>; otherwise they are reported as an empty <span class="type"><a href="language.types.string.html" class="type string">string</a></span>. <div class="informalexample"> <div class="example-contents"> <div class="phpcode"><code><span style="color: #000000"> <span style="color: #0000BB"><?php<br />preg_match</span><span style="color: #007700">(</span><span style="color: #DD0000">'/(a)(b)*(c)/'</span><span style="color: #007700">, </span><span style="color: #DD0000">'ac'</span><span style="color: #007700">, </span><span style="color: #0000BB">$matches</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">$matches</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">preg_match</span><span style="color: #007700">(</span><span style="color: #DD0000">'/(a)(b)*(c)/'</span><span style="color: #007700">, </span><span style="color: #DD0000">'ac'</span><span style="color: #007700">, </span><span style="color: #0000BB">$matches</span><span style="color: #007700">, </span><span style="color: #0000BB">PREG_UNMATCHED_AS_NULL</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">$matches</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span> </span> </code></div> </div> <p class="para">The above example will output:</p> <div class="example-contents screen"> <div class="cdata"><pre> array(4) { [0]=> string(2) "ac" [1]=> string(1) "a" [2]=> string(0) "" [3]=> string(1) "c" } array(4) { [0]=> string(2) "ac" [1]=> string(1) "a" [2]=> NULL [3]=> string(1) "c" } </pre></div> </div> </div> </p> </dd> </dl> </p> </dd> <dt> <code class="parameter">offset</code></dt> <dd> <p class="para"> Normally, the search starts from the beginning of the subject string. The optional parameter <code class="parameter">offset</code> can be used to specify the alternate place from which to start the search (in bytes). </p> <blockquote class="note"><p><strong class="note">Note</strong>: <p class="para"> Using <code class="parameter">offset</code> is not equivalent to passing <code class="code">substr($subject, $offset)</code> to <span class="function"><strong>preg_match()</strong></span> in place of the subject string, because <code class="parameter">pattern</code> can contain assertions such as <em class="emphasis">^</em>, <em class="emphasis">$</em> or <em class="emphasis">(?<=x)</em>. Compare: <div class="informalexample"> <div class="example-contents"> <div class="phpcode"><code><span style="color: #000000"> <span style="color: #0000BB"><?php<br />$subject </span><span style="color: #007700">= </span><span style="color: #DD0000">"abcdef"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$pattern </span><span style="color: #007700">= </span><span style="color: #DD0000">'/^def/'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">preg_match</span><span style="color: #007700">(</span><span style="color: #0000BB">$pattern</span><span style="color: #007700">, </span><span style="color: #0000BB">$subject</span><span style="color: #007700">, </span><span style="color: #0000BB">$matches</span><span style="color: #007700">, </span><span style="color: #0000BB">PREG_OFFSET_CAPTURE</span><span style="color: #007700">, </span><span style="color: #0000BB">3</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$matches</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span> </span> </code></div> </div> <p class="para">The above example will output:</p> <div class="example-contents screen"> <div class="cdata"><pre> Array ( ) </pre></div> </div> <p class="para"> while this example </p> <div class="example-contents"> <div class="phpcode"><code><span style="color: #000000"> <span style="color: #0000BB"><?php<br />$subject </span><span style="color: #007700">= </span><span style="color: #DD0000">"abcdef"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$pattern </span><span style="color: #007700">= </span><span style="color: #DD0000">'/^def/'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">preg_match</span><span style="color: #007700">(</span><span style="color: #0000BB">$pattern</span><span style="color: #007700">, </span><span style="color: #0000BB">substr</span><span style="color: #007700">(</span><span style="color: #0000BB">$subject</span><span style="color: #007700">,</span><span style="color: #0000BB">3</span><span style="color: #007700">), </span><span style="color: #0000BB">$matches</span><span style="color: #007700">, </span><span style="color: #0000BB">PREG_OFFSET_CAPTURE</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$matches</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span> </span> </code></div> </div> <p class="para"> will produce </p> <div class="example-contents screen"> <div class="cdata"><pre> Array ( [0] => Array ( [0] => def [1] => 0 ) ) </pre></div> </div> <p class="para"> Alternatively, to avoid using <span class="function"><a href="function.substr.html" class="function">substr()</a></span>, use the <em>\G</em> assertion rather than the <em>^</em> anchor, or the <em>A</em> modifier instead, both of which work with the <code class="parameter">offset</code> parameter. </p> </div> </p> </p></blockquote> </dd> </dl> </p> </div> <div class="refsect1 returnvalues" id="refsect1-function.preg-match-returnvalues"> <h3 class="title">Return Values</h3> <p class="para"> <span class="function"><strong>preg_match()</strong></span> returns 1 if the <code class="parameter">pattern</code> matches given <code class="parameter">subject</code>, 0 if it does not, or <strong><code>FALSE</code></strong> if an error occurred. </p> <div class="warning"><strong class="warning">Warning</strong><p class="simpara">This function may return Boolean <strong><code>FALSE</code></strong>, but may also return a non-Boolean value which evaluates to <strong><code>FALSE</code></strong>. Please read the section on <a href="language.types.boolean.html" class="link">Booleans</a> for more information. Use <a href="language.operators.comparison.html" class="link">the === operator</a> for testing the return value of this function.</p></div> </div> <div class="refsect1 changelog" id="refsect1-function.preg-match-changelog"> <h3 class="title">Changelog</h3> <p class="para"> <table class="doctable informaltable"> <thead> <tr> <th>Version</th> <th>Description</th> </tr> </thead> <tbody class="tbody"> <tr> <td>7.2.0</td> <td> The <strong><code>PREG_UNMATCHED_AS_NULL</code></strong> is now supported for the <code class="parameter">$flags</code> parameter. </td> </tr> <tr> <td>5.3.6</td> <td> Returns <strong><code>FALSE</code></strong> if <code class="parameter">offset</code> is higher than <code class="parameter">subject</code> length. </td> </tr> <tr> <td>5.2.2</td> <td> Named subpatterns now accept the syntax <em>(?<name>)</em> and <em>(?'name')</em> as well as <em>(?P<name>)</em>. Previous versions accepted only <em>(?P<name>)</em>. </td> </tr> </tbody> </table> </p> </div> <div class="refsect1 examples" id="refsect1-function.preg-match-examples"> <h3 class="title">Examples</h3> <p class="para"> <div class="example" id="example-5989"> <p><strong>Example #1 Find the string of text "php"</strong></p> <div class="example-contents"> <div class="phpcode"><code><span style="color: #000000"> <span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">// The "i" after the pattern delimiter indicates a case-insensitive search<br /></span><span style="color: #007700">if (</span><span style="color: #0000BB">preg_match</span><span style="color: #007700">(</span><span style="color: #DD0000">"/php/i"</span><span style="color: #007700">, </span><span style="color: #DD0000">"PHP is the web scripting language of choice."</span><span style="color: #007700">)) {<br /> echo </span><span style="color: #DD0000">"A match was found."</span><span style="color: #007700">;<br />} else {<br /> echo </span><span style="color: #DD0000">"A match was not found."</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?></span> </span> </code></div> </div> </div> </p> <p class="para"> <div class="example" id="example-5990"> <p><strong>Example #2 Find the word "web"</strong></p> <div class="example-contents"> <div class="phpcode"><code><span style="color: #000000"> <span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">/* The \b in the pattern indicates a word boundary, so only the distinct<br /> * word "web" is matched, and not a word partial like "webbing" or "cobweb" */<br /></span><span style="color: #007700">if (</span><span style="color: #0000BB">preg_match</span><span style="color: #007700">(</span><span style="color: #DD0000">"/\bweb\b/i"</span><span style="color: #007700">, </span><span style="color: #DD0000">"PHP is the web scripting language of choice."</span><span style="color: #007700">)) {<br /> echo </span><span style="color: #DD0000">"A match was found."</span><span style="color: #007700">;<br />} else {<br /> echo </span><span style="color: #DD0000">"A match was not found."</span><span style="color: #007700">;<br />}<br /><br />if (</span><span style="color: #0000BB">preg_match</span><span style="color: #007700">(</span><span style="color: #DD0000">"/\bweb\b/i"</span><span style="color: #007700">, </span><span style="color: #DD0000">"PHP is the website scripting language of choice."</span><span style="color: #007700">)) {<br /> echo </span><span style="color: #DD0000">"A match was found."</span><span style="color: #007700">;<br />} else {<br /> echo </span><span style="color: #DD0000">"A match was not found."</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?></span> </span> </code></div> </div> </div> </p> <p class="para"> <div class="example" id="example-5991"> <p><strong>Example #3 Getting the domain name out of a URL</strong></p> <div class="example-contents"> <div class="phpcode"><code><span style="color: #000000"> <span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">// get host name from URL<br /></span><span style="color: #0000BB">preg_match</span><span style="color: #007700">(</span><span style="color: #DD0000">'@^(?:http://)?([^/]+)@i'</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">"http://www.php.net/index.html"</span><span style="color: #007700">, </span><span style="color: #0000BB">$matches</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$host </span><span style="color: #007700">= </span><span style="color: #0000BB">$matches</span><span style="color: #007700">[</span><span style="color: #0000BB">1</span><span style="color: #007700">];<br /><br /></span><span style="color: #FF8000">// get last two segments of host name<br /></span><span style="color: #0000BB">preg_match</span><span style="color: #007700">(</span><span style="color: #DD0000">'/[^.]+\.[^.]+$/'</span><span style="color: #007700">, </span><span style="color: #0000BB">$host</span><span style="color: #007700">, </span><span style="color: #0000BB">$matches</span><span style="color: #007700">);<br />echo </span><span style="color: #DD0000">"domain name is: </span><span style="color: #007700">{</span><span style="color: #0000BB">$matches</span><span style="color: #007700">[</span><span style="color: #0000BB">0</span><span style="color: #007700">]}</span><span style="color: #DD0000">\n"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">?></span> </span> </code></div> </div> <div class="example-contents"><p>The above example will output:</p></div> <div class="example-contents screen"> <div class="cdata"><pre> domain name is: php.net </pre></div> </div> </div> </p> <p class="para"> <div class="example" id="example-5992"> <p><strong>Example #4 Using named subpattern</strong></p> <div class="example-contents"> <div class="phpcode"><code><span style="color: #000000"> <span style="color: #0000BB"><?php<br /><br />$str </span><span style="color: #007700">= </span><span style="color: #DD0000">'foobar: 2008'</span><span style="color: #007700">;<br /><br /></span><span style="color: #0000BB">preg_match</span><span style="color: #007700">(</span><span style="color: #DD0000">'/(?P<name>\w+): (?P<digit>\d+)/'</span><span style="color: #007700">, </span><span style="color: #0000BB">$str</span><span style="color: #007700">, </span><span style="color: #0000BB">$matches</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">/* This also works in PHP 5.2.2 (PCRE 7.0) and later, however <br /> * the above form is recommended for backwards compatibility */<br />// preg_match('/(?<name>\w+): (?<digit>\d+)/', $str, $matches);<br /><br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$matches</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">?></span> </span> </code></div> </div> <div class="example-contents"><p>The above example will output:</p></div> <div class="example-contents screen"> <div class="cdata"><pre> Array ( [0] => foobar: 2008 [name] => foobar [1] => foobar [digit] => 2008 [2] => 2008 ) </pre></div> </div> </div> </p> </div> <div class="refsect1 notes" id="refsect1-function.preg-match-notes"> <h3 class="title">Notes</h3> <div class="tip"><strong class="tip">Tip</strong> <p class="para"> Do not use <span class="function"><strong>preg_match()</strong></span> if you only want to check if one string is contained in another string. Use <span class="function"><a href="function.strpos.html" class="function">strpos()</a></span> instead as it will be faster. </p> </div> </div> <div class="refsect1 seealso" id="refsect1-function.preg-match-seealso"> <h3 class="title">See Also</h3> <p class="para"> <ul class="simplelist"> <li class="member"><a href="pcre.pattern.html" class="link">PCRE Patterns</a></li> <li class="member"><span class="function"><a href="function.preg-quote.html" class="function" rel="rdfs-seeAlso">preg_quote()</a> - Quote regular expression characters</span></li> <li class="member"><span class="function"><a href="function.preg-match-all.html" class="function" rel="rdfs-seeAlso">preg_match_all()</a> - Perform a global regular expression match</span></li> <li class="member"><span class="function"><a href="function.preg-replace.html" class="function" rel="rdfs-seeAlso">preg_replace()</a> - Perform a regular expression search and replace</span></li> <li class="member"><span class="function"><a href="function.preg-split.html" class="function" rel="rdfs-seeAlso">preg_split()</a> - Split string by a regular expression</span></li> <li class="member"><span class="function"><a href="function.preg-last-error.html" class="function" rel="rdfs-seeAlso">preg_last_error()</a> - Returns the error code of the last PCRE regex execution</span></li> </ul> </p> </div> </div><hr /><div class="manualnavbar" style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.preg-match-all.html">preg_match_all</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.preg-quote.html">preg_quote</a></div> <div class="up"><a href="ref.pcre.html">PCRE Functions</a></div> <div class="home"><a href="index.html">PHP Manual</a></div> </div></body></html>