超全局变量

static

静态变量:初始化一次,再次调用时会记录下来上次值.变量不会销毁.再PHP执行前就已经写入内存

<?PHP

  function check_static(){
    static $num = 2;
  	$num  *=2;
  	echo $num,"</br>";
  }

check_static();			//输出:4
check_static();			//输出:8

$GLOBALS

全局变量,其中包含_GET,_POST,_COOKIE,_SERVER,_ENV,_REQUEST,_FILES,GLOBALS($GLOBALS[’_GET’],与$_GET效果一样,)

其中GLOBALS中可获取所有自定义变量,可在页面任意处使用

<?php
    $num = 10;
    function check_globals ()
    {
        echo $GLOBALS['num'],'</br>';	//10
        echo $GLOBALS['str'],'</br>';	//This is str
        var_dump( $GLOBALS['_SERVER']);	//与$_SERVER相等
        var_dump( $GLOBALS);	//包含:(array)_GET,(array)_POST,(array)_COOKIE,(array)_SERVER,(array)_ENV,(array)_REQUEST,(array)_FILES,(array)GLOBALS
    }
    $str = "This is str";
    check_globals();