A brief summary of commonly used magic constants and superglobal variables in PHP

This article brings you a brief summary of the commonly used magic constants and superglobal variables in PHP. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

1. Commonly used magic constants

//获取当前文件所在的目录，如：D:\web
echo __DIR__;
//获取当前文件的绝对路径，目录+文件名，如：D:\web\index.php
echo __FILE__;
//当前运行脚本的类名称
echo __CLASS__;
//当前运行脚本的函数名称
echo __FUNCTION__;
//当前运行脚本的方法名称
echo __METHOD__;
/*注：非类方法体内，__FUNCTION__等同于__METHOD__；
     类方法体中__METHOD__会包含类名称，如：ClassName::MethodName*/

2. Commonly used super global variables

//$_COOKIE由HTTP传递给脚本的变量数组，记录在客户端
print_r($_COOKIE);
$_COOKIE['var_name'] = 'cookie';    //赋值
echo $_COOKIE['var_name'];        //取值
//$_SESSION存储在服务器端的变量数组，需要依赖$_COOKIE
session_start();//开启session,需写在在文件开头
print_r($_SESSION);
$_SESSION['var_name'] = 'session';    //赋值
echo $_SESSION['var_name'];        //取值
//$_GET获取URL携带的参数
echo $_GET['param'];
//$_POST获取HTTP使用post方式传递的参数
echo $_POST['param'];

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