function.strrpos.html
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html> <head> <title>Find position of last occurrence of a char in a string</title> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> </head> <body><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.strripos.html">strripos</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.strspn.html">strspn</a></div> <div class="up"><a href="ref.strings.html">String Functions</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div><hr /><div id="function.strrpos" class="refentry"> <div class="refnamediv"> <h1 class="refname">strrpos</h1> <p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">strrpos</span> — <span class="dc-title">Find position of last occurrence of a char in a string</span></p> </div> <div class="refsect1 description"> <h3 class="title">Description</h3> <div class="methodsynopsis dc-description"> <span class="type">int</span> <span class="methodname"><b><b>strrpos</b></b></span> ( <span class="methodparam"><span class="type">string</span> <tt class="parameter">$haystack</tt></span> , <span class="methodparam"><span class="type">string</span> <tt class="parameter">$needle</tt></span> [, <span class="methodparam"><span class="type">int</span> <tt class="parameter">$offset</tt></span> ] )</div> <p class="para rdfs-comment"> Returns the numeric position of the last occurrence of <i><tt class="parameter">needle</tt></i> in the <i><tt class="parameter">haystack</tt></i> string. Note that the needle in this case can only be a single character in PHP 4. If a string is passed as the needle, then only the first character of that string will be used. </p> <p class="para"> If <i><tt class="parameter">needle</tt></i> is not found, returns <b><tt>FALSE</tt></b>. </p> <p class="para"> It is easy to mistake the return values for "character found at position 0" and "character not found". Here's how to detect the difference: <div class="informalexample"> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br /><br /></span><span style="color: #FF8000">// in PHP 4.0.0 and newer:<br /></span><span style="color: #0000BB">$pos </span><span style="color: #007700">= </span><span style="color: #0000BB">strrpos</span><span style="color: #007700">(</span><span style="color: #0000BB">$mystring</span><span style="color: #007700">, </span><span style="color: #DD0000">"b"</span><span style="color: #007700">);<br />if (</span><span style="color: #0000BB">$pos </span><span style="color: #007700">=== </span><span style="color: #0000BB">false</span><span style="color: #007700">) { </span><span style="color: #FF8000">// note: three equal signs<br /> // not found...<br /></span><span style="color: #007700">}<br /><br /></span><span style="color: #FF8000">// in versions older than 4.0.0:<br /></span><span style="color: #0000BB">$pos </span><span style="color: #007700">= </span><span style="color: #0000BB">strrpos</span><span style="color: #007700">(</span><span style="color: #0000BB">$mystring</span><span style="color: #007700">, </span><span style="color: #DD0000">"b"</span><span style="color: #007700">);<br />if (</span><span style="color: #0000BB">is_bool</span><span style="color: #007700">(</span><span style="color: #0000BB">$pos</span><span style="color: #007700">) && !</span><span style="color: #0000BB">$pos</span><span style="color: #007700">) {<br /> </span><span style="color: #FF8000">// not found...<br /></span><span style="color: #007700">}<br /></span><span style="color: #0000BB">?></span></span></code></div> </div> </div> </p> <p class="para"> If <i><tt class="parameter">needle</tt></i> is not a string, it is converted to an integer and applied as the ordinal value of a character. </p> <blockquote><p><b class="note">Note</b>: <span class="simpara"> As of PHP 5.0.0 <i><tt class="parameter">offset</tt></i> may be specified to begin searching an arbitrary number of characters into the string. Negative values will stop searching at an arbitrary point prior to the end of the string. </span> </p></blockquote> <blockquote><p><b class="note">Note</b>: <span class="simpara"> The <i><tt class="parameter">needle</tt></i> may be a string of more than one character as of PHP 5.0.0. </span> </p></blockquote> </div> <div class="refsect1 parameters"> <h3 class="title">Parameters</h3> <p class="para"> <dl> <dt> <span class="term"><i><tt class="parameter">haystack</tt></i></span> <dd> <p class="para"> </p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">needle</tt></i></span> <dd> <p class="para"> </p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">offset</tt></i></span> <dd> <p class="para"> </p> </dd> </dt> </dl> </p> </div> <div class="refsect1 returnvalues"> <h3 class="title">Return Values</h3> <p class="para"> </p> </div> <div class="refsect1 seealso"> <h3 class="title">See Also</h3> <p class="para"> <ul class="simplelist"> <li class="member"><a href="function.strpos.html" class="function" rel="rdfs-seeAlso">strpos()</a></li> <li class="member"><a href="function.strripos.html" class="function" rel="rdfs-seeAlso">strripos()</a></li> <li class="member"><a href="function.strrchr.html" class="function" rel="rdfs-seeAlso">strrchr()</a></li> <li class="member"><a href="function.substr.html" class="function" rel="rdfs-seeAlso">substr()</a></li> <li class="member"><a href="function.stristr.html" class="function" rel="rdfs-seeAlso">stristr()</a></li> <li class="member"><a href="function.strstr.html" class="function" rel="rdfs-seeAlso">strstr()</a></li> </ul> </p> </div></div><hr /><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.strripos.html">strripos</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.strspn.html">strspn</a></div> <div class="up"><a href="ref.strings.html">String Functions</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div></body></html>⌨️ 快捷键说明
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