如何在php函數中引用全局變量

php函數中對全局變量的引用。代碼如下：

<?php
$var1 = "#####";
$var2 = "&&&&&";
function global_references($use_globals) {
global $var1, $var2;
if (!$use_globals) {
$var2 =&$var1; //1
} else {
$GLOBALS["var2"] =&$var1; //2
}
}
global_references(false);
echo "var2 is set to '$var2'<br/>";
global_references(true);
echo "var2 is set to '$var2'<br/>";
?>

輸出的結果如下：
var2 is set to '&&&&&'
var2 is set to '#####'
可見，上面的代碼中：
$var2 =&$var1; //1
只對函數內部可見。
而
$GLOBALS["var2"] =&$var1; //2
在全局范圍內可見。