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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>Examples</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="session.constants.html">Predefined Constants</a></div> <div class="next" style="text-align: right; float: right;"><a href="session.idpassing.html">Passing the Session ID</a></div> <div class="up"><a href="book.session.html">Sessions</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div><hr /><div> <h1>Examples</h1><h2>Table of Contents</h2><ul class="chunklist chunklist_appendix"><li><a href="session.idpassing.html">Passing the Session ID</a></li><li><a href="session.customhandler.html">Custom Session Handlers</a></li></ul> <div id="session.examples.basic" class="section"> <blockquote><p><b class="note">Note</b>: As of PHP 4.1.0, <var class="varname"><a href="reserved.variables.session.html" class="classname">$_SESSION</a></var> is available as a global variable just like <var class="varname"><a href="reserved.variables.post.html" class="classname">$_POST</a></var>, <var class="varname"><a href="reserved.variables.get.html" class="classname">$_GET</a></var>, <var class="varname"><a href="reserved.variables.request.html" class="classname">$_REQUEST</a></var> and so on. Unlike <var class="varname">$HTTP_SESSION_VARS</var>, <var class="varname"><a href="reserved.variables.session.html" class="classname">$_SESSION</a></var> is always global. Therefore, you do not need to use the <a href="language.variables.scope.html" class="link"><strong class="command">global</strong></a> keyword for <var class="varname"><a href="reserved.variables.session.html" class="classname">$_SESSION</a></var>. Please note that this documentation has been changed to use <var class="varname"><a href="reserved.variables.session.html" class="classname">$_SESSION</a></var> everywhere. You can substitute <var class="varname">$HTTP_SESSION_VARS</var> for <var class="varname"><a href="reserved.variables.session.html" class="classname">$_SESSION</a></var>, if you prefer the former. Also note that you must start your session using <a href="function.session-start.html" class="function">session_start()</a> before use of <var class="varname"><a href="reserved.variables.session.html" class="classname">$_SESSION</a></var> becomes available. <br /> The keys in the <var class="varname"><a href="reserved.variables.session.html" class="classname">$_SESSION</a></var> associative array are subject to the same limitations as regular variable names in PHP, i.e. they cannot start with a number and must start with a letter or underscore. For more details see the section on <a href="language.variables.html" class="link">variables</a> in this manual. <br /> </p></blockquote> <p class="para"> If <a href="ini.core.html#ini.register-globals" class="link">register_globals</a> is disabled, only members of the global associative array <var class="varname"><a href="reserved.variables.session.html" class="classname">$_SESSION</a></var> can be registered as session variables. The restored session variables will only be available in the array <var class="varname"><a href="reserved.variables.session.html" class="classname">$_SESSION</a></var>. </p> <p class="para"> Use of <var class="varname"><a href="reserved.variables.session.html" class="classname">$_SESSION</a></var> (or <var class="varname">$HTTP_SESSION_VARS</var> with PHP 4.0.6 or less) is recommended for improved security and code readability. With <var class="varname"><a href="reserved.variables.session.html" class="classname">$_SESSION</a></var>, there is no need to use the <a href="function.session-register.html" class="function">session_register()</a>, <a href="function.session-unregister.html" class="function">session_unregister()</a>, <a href="function.session-is-registered.html" class="function">session_is_registered()</a> functions. Session variables are accessible like any other variables. <div class="example"> <p><b>Example #1 Registering a variable with <var class="varname"><a href="reserved.variables.session.html" class="classname">$_SESSION</a></var>. </b></p> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br />session_start</span><span style="color: #007700">();<br /></span><span style="color: #FF8000">// Use $HTTP_SESSION_VARS with PHP 4.0.6 or less<br /></span><span style="color: #007700">if (!isset(</span><span style="color: #0000BB">$_SESSION</span><span style="color: #007700">[</span><span style="color: #DD0000">'count'</span><span style="color: #007700">])) {<br /> </span><span style="color: #0000BB">$_SESSION</span><span style="color: #007700">[</span><span style="color: #DD0000">'count'</span><span style="color: #007700">] = </span><span style="color: #0000BB">0</span><span style="color: #007700">;<br />} else {<br /> </span><span style="color: #0000BB">$_SESSION</span><span style="color: #007700">[</span><span style="color: #DD0000">'count'</span><span style="color: #007700">]++;<br />}<br /></span><span style="color: #0000BB">?></span></span></code></div> </div> </div> <div class="example"> <p><b>Example #2 Unregistering a variable with <var class="varname"><a href="reserved.variables.session.html" class="classname">$_SESSION</a></var> and <a href="ini.core.html#ini.register-globals" class="link">register_globals</a> disabled. </b></p> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br />session_start</span><span style="color: #007700">();<br /></span><span style="color: #FF8000">// Use $HTTP_SESSION_VARS with PHP 4.0.6 or less<br /></span><span style="color: #007700">unset(</span><span style="color: #0000BB">$_SESSION</span><span style="color: #007700">[</span><span style="color: #DD0000">'count'</span><span style="color: #007700">]);<br /></span><span style="color: #0000BB">?></span></span></code></div> </div> </div> </p> <p class="para"> <div class="caution"><b class="caution">Caution</b> <p class="para"> Do NOT unset the whole <var class="varname"><a href="reserved.variables.session.html" class="classname">$_SESSION</a></var> with <i>unset($_SESSION)</i> as this will disable the registering of session variables through the <var class="varname"><a href="reserved.variables.session.html" class="classname">$_SESSION</a></var> superglobal. </p> </div> </p> <div class="warning"><b class="warning">Warning</b> <p class="para"> You can't use references in session variables as there is no feasible way to restore a reference to another variable. </p> </div> <p class="para"> If <a href="ini.core.html#ini.register-globals" class="link">register_globals</a> is enabled, then each global variable can be registered as session variable. Upon a restart of a session, these variables will be restored to corresponding global variables. Since PHP must know which global variables are registered as session variables, users need to register variables with <a href="function.session-register.html" class="function">session_register()</a> function. You can avoid this by simply setting entries in <var class="varname"><a href="reserved.variables.session.html" class="classname">$_SESSION</a></var>. <div class="caution"><b class="caution">Caution</b> <p class="para"> Before PHP 4.3.0, if you are using <var class="varname"><a href="reserved.variables.session.html" class="classname">$_SESSION</a></var> and you have disabled <a href="ini.core.html#ini.register-globals" class="link">register_globals</a>, don't use <a href="function.session-register.html" class="function">session_register()</a>, <a href="function.session-is-registered.html" class="function">session_is_registered()</a> or <a href="function.session-unregister.html" class="function">session_unregister()</a>. Disabling <a href="ini.core.html#ini.register-globals" class="link">register_globals</a> is recommended for both security and performance reasons. </p> </div> </p> <p class="para"> If <a href="ini.core.html#ini.register-globals" class="link">register_globals</a> is enabled, then the global variables and the <var class="varname"><a href="reserved.variables.session.html" class="classname">$_SESSION</a></var> entries will automatically reference the same values which were registered in the prior session instance. However, if the variable is registered by <var class="varname"><a href="reserved.variables.session.html" class="classname">$_SESSION</a></var> then the global variable is available since the next request. </p> <p class="para"> There is a defect in PHP 4.2.3 and earlier. If you register a new session variable by using <a href="function.session-register.html" class="function">session_register()</a>, the entry in the global scope and the <var class="varname"><a href="reserved.variables.session.html" class="classname">$_SESSION</a></var> entry will not reference the same value until the next <a href="function.session-start.html" class="function">session_start()</a>. I.e. a modification to the newly registered global variable will not be reflected by the <var class="varname"><a href="reserved.variables.session.html" class="classname">$_SESSION</a></var> entry. This has been corrected in PHP 4.3.0. </p> </div> </div><hr /><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="session.constants.html">Predefined Constants</a></div> <div class="next" style="text-align: right; float: right;"><a href="session.idpassing.html">Passing the Session ID</a></div> <div class="up"><a href="book.session.html">Sessions</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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