foreach 對象引用

foreach $arr as $v, 如果$v是一個對象，則創建的是一個引用，不是拷貝建立新值。所以在一個function 裏面 return $v, 在function 外修改了$v的值，會直接作用到$arr.

<?php
class A
{
public $a;
}
$t1 = new A;
$t1->a  = "test 1";
$t2 = new A;
$t2->a = "test 2";
$f = array($t1,$t2);
$i = 3;
foreach($f as $v)
{    
    $v->a = "test ".$i;
    $i++;
}
//print_r($f);

function test1($t1,$t2)
{

$f = array($t1,$t2);
print_r($f);
$i = 3;
foreach($f as $v)
{    
    $v->a = "test ".$i;
    $i++;
    return $v;
}

}
$t3 = test1($t1,$t2);
$t3->a ="test 7";
test1($t1,$t2);
?>

輸出結果：

Array( [0] => A Object ( [a] => test 3 ) [1] => A Object ( [a] => test 4 ))Array( [0] => A Object ( [a] => test 7 ) [1] => A Object ( [a] => test 4 ))