请教大家个问题关于global

global $var1,$var2;
$var1 = 1;  
$var2 = 2;  
function test(){  
     $var2 = &$var1;  
}  
test();  
echo $var2;  

global $var1,$var2;
$var1 = 1;  
$var2 = 2;  
$var2 = &$var1;  
echo $var2;