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https://github.com/sigmasternchen/php-doc-en
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c148211fa2
git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@172416 c90b9560-bf6c-de11-be94-00142212c4b1
97 lines
3.2 KiB
XML
97 lines
3.2 KiB
XML
<?xml version="1.0" encoding="iso-8859-1"?>
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<!-- $Revision: 1.16 $ -->
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<!-- splitted from ./en/functions/http.xml, last change in rev 1.7 -->
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<refentry id="function.headers-sent">
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<refnamediv>
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<refname>headers_sent</refname>
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<refpurpose>Checks if or where headers have been sent</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Description</title>
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<methodsynopsis>
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<type>bool</type><methodname>headers_sent</methodname>
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<methodparam choice="opt"><type>string</type><parameter role="reference">file</parameter></methodparam>
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<methodparam choice="opt"><type>int</type><parameter role="reference">line</parameter></methodparam>
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</methodsynopsis>
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<simpara>
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<function>headers_sent</function> will return &false; if no HTTP headers
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have already been sent or &true; otherwise. If the optional
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<parameter>file</parameter> and <parameter>line</parameter> parameters
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are set, <function>headers_sent</function> will put the PHP source
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file name and line number where output started in the <parameter>file</parameter>
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and <parameter>line</parameter> variables.
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</simpara>
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<simpara>
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You can't add any more header lines using the <function>header</function>
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function once the header block has already been sent. Using this function
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you can at least prevent getting HTTP header related error messages.
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Another option is to use <link linkend="ref.outcontrol">Output Buffering</link>.
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</simpara>
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<note>
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<simpara>
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The optional <parameter>file</parameter> and <parameter>line</parameter>
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parameters where added in PHP 4.3.0.
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</simpara>
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</note>
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<para>
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<example>
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<title>Examples using <function>headers_sent</function></title>
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<programlisting role="php">
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<![CDATA[
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<?php
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// If no headers are sent, send one
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if (!headers_sent()) {
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header('Location: http://www.example.com/');
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exit;
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}
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// An example using the optional file and line parameters, as of PHP 4.3.0
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// Note that $filename and $linenum are passed in for later use.
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// Do not assign them values beforehand.
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if (!headers_sent($filename, $linenum)) {
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header('Location: http://www.example.com/');
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exit;
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// You would most likely trigger an error here.
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} else {
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echo "Headers already sent in $filename on line $linenum\n" .
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"Cannot redirect, for now please click this <a " .
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"href=\"http://www.example.com\">link</a> instead\n";
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exit;
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}
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?>
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]]>
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</programlisting>
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</example>
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</para>
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<para>
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See also <function>ob_start</function>, <function>trigger_error</function>,
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and <function>header</function> for a more detailed discussion of the
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matters involved.
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</para>
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</refsect1>
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</refentry>
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<!-- Keep this comment at the end of the file
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Local variables:
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mode: sgml
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sgml-omittag:t
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sgml-shorttag:t
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sgml-minimize-attributes:nil
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sgml-always-quote-attributes:t
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sgml-indent-step:1
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sgml-indent-data:t
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indent-tabs-mode:nil
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sgml-parent-document:nil
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sgml-default-dtd-file:"../../../../manual.ced"
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sgml-exposed-tags:nil
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sgml-local-catalogs:nil
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sgml-local-ecat-files:nil
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End:
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vim600: syn=xml fen fdm=syntax fdl=2 si
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vim: et tw=78 syn=sgml
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vi: ts=1 sw=1
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-->
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