先看下面的代碼：

<?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。