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https://github.com/sigmasternchen/php-doc-en
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git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@146741 c90b9560-bf6c-de11-be94-00142212c4b1
147 lines
4.5 KiB
XML
147 lines
4.5 KiB
XML
<?xml version="1.0" encoding="iso-8859-1"?>
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<!-- $Revision: 1.7 $ -->
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<!-- splitted from ./en/functions/outcontrol.xml, last change in rev 1.1 -->
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<refentry id="function.ob-start">
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<refnamediv>
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<refname>ob_start</refname>
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<refpurpose>Turn on output buffering</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>ob_start</methodname>
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<methodparam choice="opt"><type>callback</type><parameter>
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output_callback
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</parameter></methodparam>
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</methodsynopsis>
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<para>
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This function will turn output buffering on. While output
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buffering is active no output is sent from the script (other than
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headers), instead the output is stored in an internal buffer.
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</para>
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<para>
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The contents of this internal buffer may be copied into a string
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variable using <function>ob_get_contents</function>. To output
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what is stored in the internal buffer, use
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<function>ob_end_flush</function>. Alternatively,
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<function>ob_end_clean</function> will silently discard the
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buffer contents.
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</para>
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<para>
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An optional <parameter>output_callback</parameter> function may
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be specified. This function takes a string as a parameter and
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should return a string. The function will be called when
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<function>ob_end_flush</function> is called, or when the output
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buffer is flushed to the browser at the end of the request. When
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<parameter>output_callback</parameter> is called, it will receive
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the contents of the output buffer as its parameter and is
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expected to return a new output buffer as a result, which will be
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sent to the browser. If the <parameter>output_callback</parameter> is not
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a callable function, this function will return &false;.
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</para>
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<note>
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<para>
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In PHP 4.0.4, <function>ob_gzhandler</function> was introduced
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to facilitate sending gz-encoded data to web browsers that
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support compressed web pages. <function>ob_gzhandler</function>
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determines what type of content encoding the browser will accept
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and will return it's output accordingly.
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</para>
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</note>
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<note>
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<para>
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Before PHP 4.3.2 this function did not return &false; in case the passed
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<parameter>output_callback</parameter> can not be executed.
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</para>
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</note>
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<para>
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Output buffers are stackable, that is, you may call
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<function>ob_start</function> while another
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<function>ob_start</function> is active. Just make
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sure that you call <function>ob_end_flush</function>
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the appropriate number of times. If multiple output callback
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functions are active, output is being filtered sequentially
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through each of them in nesting order.
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</para>
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<para>
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<function>ob_end_clean</function>,
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<function>ob_end_flush</function>, <function>ob_clean</function>,
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<function>ob_flush</function> and <function>ob_start</function>
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may not be called from a callback function. If you call them from
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callback function, the behavior is undefined. If you would like to
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delete the contents of a buffer, return "" (a null string) from callback
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function.
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</para>
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<para>
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<example>
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<title>User defined callback function example</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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function callback($buffer) {
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// replace all the apples with oranges
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return (str_replace("apples", "oranges", $buffer));
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}
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ob_start("callback");
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?>
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<html>
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<body>
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<p>It's like comparing apples to oranges.
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</body>
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</html>
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<?php
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ob_end_flush();
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?>
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]]>
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</programlisting>
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<para>
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Would produce:
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</para>
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<screen>
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<![CDATA[
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<html>
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<body>
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<p>It's like comparing oranges to oranges.
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</body>
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</html>
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]]>
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</screen>
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</example>
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</para>
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<para>
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See also <function>ob_get_contents</function>,
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<function>ob_end_flush</function>,
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<function>ob_end_clean</function>,
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<function>ob_implicit_flush</function> and
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<function>ob_gzhandler</function>.
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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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