函數參數為數組時傳值、傳址的區別，請高手結合執行個體講解

$json = '[{"id":27,"children":[{"id":30,"children":[{"id":31}]}]},{"id":28,"children":[{"id":29}]},{"id":32}]';
$arry = json_decode($json,true);
print_r($arry);
echo"
";
print_r(foo($arry));
echo"
";
function foo($ar, $level=0, $parent=0,&$res=array()) {
foreach($ar as $v) {
$t = array();
$v['level'] = $level;
$v['parent'] = $parent;
if(isset($v['children'])) {
$t = $v['children'];
unset($v['children']);
}
$res[] = $v;
if($t) foo($t, $level+1, $v['id'], $res);
}
return $res;
}
?>
Array ( [0] => Array ( [id] => 27 [children] => Array ( [0] => Array ( [id] => 30 [children] => Array ( [0] => Array ( [id] => 31 ) ) ) ) ) [1] => Array ( [id] => 28 [children] => Array ( [0] => Array ( [id] => 29 ) ) ) [2] => Array ( [id] => 32 ) )

Array ( [0] => Array ( [id] => 27 [level] => 0 [parent] => 0 ) [1] => Array ( [id] => 30 [level] => 1 [parent] => 27 ) [2] => Array ( [id] => 31 [level] => 2 [parent] => 30 ) [3] => Array ( [id] => 28 [level] => 0 [parent] => 0 ) [4] => Array ( [id] => 29 [level] => 1 [parent] => 28 ) [5] => Array ( [id] => 32 [level] => 0 [parent] => 0 ) )

如果是這樣
function foo($ar, $level=0, $parent=0, $res=array()) {
foreach($ar as $v) {
$t = array();
$v['level'] = $level;
$v['parent'] = $parent;
if(isset($v['children'])) {
$t = $v['children'];
unset($v['children']);
}
$res[] = $v;
if($t) foo($t, $level+1, $v['id'], $res);
}
return $res;
}
結果 則為：
Array ( [0] => Array ( [id] => 27 [level] => 0 [parent] => 0 ) [1] => Array ( [id] => 28 [level] => 0 [parent] => 0 ) [2] => Array ( [id] => 32 [level] => 0 [parent] => 0 ) )
請高手結合此執行個體，講解下 傳值、傳址的區別，謝謝。

回複討論(解決方案)

值傳遞：
拷貝一份未經處理資料進行操作，不改變原值。
引用傳遞：
操作未經處理資料，操作過後未經處理資料會改變。

數組值傳遞執行個體代碼：output:array(2) {  [0]=>  string(1) "a"  [1]=>  string(1) "b"}數組引用傳遞outpout:array(1) {  [0]=>  string(2) "dd"}

參考這個看看吧：http://www.cnblogs.com/zcy_soft/archive/2011/12/10/2283570.html

$res[] = $v;
if($t) foo($t, $level+1, $v['id'], $res)
----這兩個語句在函數 foo 內部，但原理是一樣的。如同樓上所舉的例子

傳值不會影響原數組，傳地址會。
例子：
地址引用

輸出：
Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 )

傳值

輸出：
Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 [4] => 5 )
Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 )

說白了就是，函數的參數，預設都是複製一份的，這樣你函數內怎麼折騰都不會影響到使用函數時傳過來的變數
加上&就不會複製，而直接用了

傳值就是多複製一份，相互不影響
引用就是同時操作同一份資料，相互影響

