global $mytext;
$mytext="外部使用global定義";
function test(){
    echo $GLOBALS['mytext']."<br>";
}
test();

function test1() {
    global $var1, $var2;
    $var2 = &$var1;
    echo "var1=".$var1."<br>";
    echo "var2=".$var2."<br>";
}
function test2() {
    $GLOBALS['var3'] = &$GLOBALS['var1'];
}
function test3() {
    global $var4;
    $var4=100;
}
$var1 = 100;
$var2 = $var3 =$var4= 0;
test1();
echo "test1執行後var2=".$var2."<br>";//輸出 0
test2();
echo "test2執行後var3=".$var3."<br>";//輸出 100
test3();
echo "test2執行後var4=".$var4."<br>";//輸出 100
 

1. 用陣列下變數名有限外部定義的變數，但是下面註釋開啟的話全部會獲取函式內部的全域性變數。

   $mytext1="外部未使用global";
   function test(){
       //global $mytext1;
       // $mytext1 = "今天是個好天氣";
       $mytext1="函式內部定義";
       echo $mytext1."<br>";
       echo $GLOBALS['mytext1']."<br>";
   }
   test

$mytext=”nihao”;function test($mytext){echo $mytext;
}
test($mytext);