php中global关键字作用和实例讲解
php中global关键字作用和实例讲解代码:
<?php
$num=10;
function fun() {
global $num; //将全局变量的$num的地址引入到函数内部相当于$num=&GLOBALS['num']
echo $num; //10
$num=100;
}
fun();
echo '<br>';
echo $num; //100
-----------------------------------
<?php
$num=10;
function fun() {
global $num;
unset($num);//销毁的是引用,不是具体的值
}
fun();
echo $num; //10
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