<!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>Checks if or where headers have been sent</title> </head> <body><div class="manualnavbar" style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.headers-list.html">headers_list</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.http-response-code.html">http_response_code</a></div> <div class="up"><a href="ref.network.html">Network Functions</a></div> <div class="home"><a href="index.html">PHP Manual</a></div> </div><hr /><div id="function.headers-sent" class="refentry"> <div class="refnamediv"> <h1 class="refname">headers_sent</h1> <p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">headers_sent</span> — <span class="dc-title">Checks if or where headers have been sent</span></p> </div> <div class="refsect1 description" id="refsect1-function.headers-sent-description"> <h3 class="title">Description</h3> <div class="methodsynopsis dc-description"> <span class="type">bool</span> <span class="methodname"><strong>headers_sent</strong></span> ([ <span class="methodparam"><span class="type">string</span> <code class="parameter reference">&$file</code></span> [, <span class="methodparam"><span class="type">int</span> <code class="parameter reference">&$line</code></span> ]] )</div> <p class="para rdfs-comment"> Checks if or where headers have been sent. </p> <p class="para"> You can't add any more header lines using the <span class="function"><a href="function.header.html" class="function">header()</a></span> function once the header block has already been sent. Using this function you can at least prevent getting HTTP header related error messages. Another option is to use <a href="ref.outcontrol.html" class="link">Output Buffering</a>. </p> </div> <div class="refsect1 parameters" id="refsect1-function.headers-sent-parameters"> <h3 class="title">Parameters</h3> <p class="para"> <dl> <dt> <span class="term"><em><code class="parameter">file</code></em></span> <dd> <p class="para"> If the optional <em><code class="parameter">file</code></em> and <em><code class="parameter">line</code></em> parameters are set, <span class="function"><strong>headers_sent()</strong></span> will put the PHP source file name and line number where output started in the <em><code class="parameter">file</code></em> and <em><code class="parameter">line</code></em> variables. </p> </dd> </dt> <dt> <span class="term"><em><code class="parameter">line</code></em></span> <dd> <p class="para"> The line number where the output started. </p> </dd> </dt> </dl> </p> </div> <div class="refsect1 returnvalues" id="refsect1-function.headers-sent-returnvalues"> <h3 class="title">Return Values</h3> <p class="para"> <span class="function"><strong>headers_sent()</strong></span> will return <strong><code>FALSE</code></strong> if no HTTP headers have already been sent or <strong><code>TRUE</code></strong> otherwise. </p> </div> <div class="refsect1 changelog" id="refsect1-function.headers-sent-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>4.3.0</td> <td> The optional <em><code class="parameter">file</code></em> and <em><code class="parameter">line</code></em> parameters were added. </td> </tr> </tbody> </table> </p> </div> <div class="refsect1 examples" id="refsect1-function.headers-sent-examples"> <h3 class="title">Examples</h3> <p class="para"> <div class="example" id="example-4487"> <p><strong>Example #1 Examples using <span class="function"><strong>headers_sent()</strong></span></strong></p> <div class="example-contents"> <div class="phpcode"><code><span style="color: #000000"> <span style="color: #0000BB"><?php<br /><br /></span><span style="color: #FF8000">// If no headers are sent, send one<br /></span><span style="color: #007700">if (!</span><span style="color: #0000BB">headers_sent</span><span style="color: #007700">()) {<br /> </span><span style="color: #0000BB">header</span><span style="color: #007700">(</span><span style="color: #DD0000">'Location: http://www.example.com/'</span><span style="color: #007700">);<br /> exit;<br />}<br /><br /></span><span style="color: #FF8000">// An example using the optional file and line parameters, as of PHP 4.3.0<br />// Note that $filename and $linenum are passed in for later use.<br />// Do not assign them values beforehand.<br /></span><span style="color: #007700">if (!</span><span style="color: #0000BB">headers_sent</span><span style="color: #007700">(</span><span style="color: #0000BB">$filename</span><span style="color: #007700">, </span><span style="color: #0000BB">$linenum</span><span style="color: #007700">)) {<br /> </span><span style="color: #0000BB">header</span><span style="color: #007700">(</span><span style="color: #DD0000">'Location: http://www.example.com/'</span><span style="color: #007700">);<br /> exit;<br /><br /></span><span style="color: #FF8000">// You would most likely trigger an error here.<br /></span><span style="color: #007700">} else {<br /><br /> echo </span><span style="color: #DD0000">"Headers already sent in </span><span style="color: #0000BB">$filename</span><span style="color: #DD0000"> on line </span><span style="color: #0000BB">$linenum</span><span style="color: #DD0000">\n" </span><span style="color: #007700">.<br /> </span><span style="color: #DD0000">"Cannot redirect, for now please click this <a " </span><span style="color: #007700">.<br /> </span><span style="color: #DD0000">"href=\"http://www.example.com\">link</a> instead\n"</span><span style="color: #007700">;<br /> exit;<br />}<br /><br /></span><span style="color: #0000BB">?></span> </span> </code></div> </div> </div> </p> </div> <div class="refsect1 notes" id="refsect1-function.headers-sent-notes"> <h3 class="title">Notes</h3> <blockquote class="note"><p><strong class="note">Note</strong>: <p class="para"> Headers will only be accessible and output when a SAPI that supports them is in use. </p> </p></blockquote> </div> <div class="refsect1 seealso" id="refsect1-function.headers-sent-seealso"> <h3 class="title">See Also</h3> <p class="para"> <ul class="simplelist"> <li class="member"> <span class="function"><a href="function.ob-start.html" class="function" rel="rdfs-seeAlso">ob_start()</a> - Turn on output buffering</span></li> <li class="member"> <span class="function"><a href="function.trigger-error.html" class="function" rel="rdfs-seeAlso">trigger_error()</a> - Generates a user-level error/warning/notice message</span></li> <li class="member"> <span class="function"><a href="function.headers-list.html" class="function" rel="rdfs-seeAlso">headers_list()</a> - Returns a list of response headers sent (or ready to send)</span></li> <li class="member"> <span class="function"><a href="function.header.html" class="function" rel="rdfs-seeAlso">header()</a> - Send a raw HTTP header</span> for a more detailed discussion of the matters involved. </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.headers-list.html">headers_list</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.http-response-code.html">http_response_code</a></div> <div class="up"><a href="ref.network.html">Network Functions</a></div> <div class="home"><a href="index.html">PHP Manual</a></div> </div></body></html>