~~~ $var1 = 1; function test(){ global $var1;//global $var1;等于$var1=&$GLOBALS['var1']; unset($var1); } test(); echo $var1;// 此处输出1 $var1 = 1; function test(){ unset($GLOBALS['var1']); } test(); echo $var1;// 此处报错PHP Notice: Undefined variable: var1 ~~~