在foreach循环中替换数组的值

Question

我在这里做错了什么？这很简单，我忽略了一些东西。我试图在foreach循环中替换数组键的值：

$arr = array(); 
$arr['firstimg'] = '123'; 
$arr['secondimg'] = '456'; 
$arr['thirdimg'] = '789'; 

foreach ($arr as $key => $value) { 

    if ($key == 'secondimg') { 
     $value = '000'; 

    } 

} 

print_r($arr); 

该数组保持不变。

Answer 1

变量$value的作用域为循环。您需要更新$arr[$key]的值。

或者，也可以如下声明循环：

foreach ($arr as $key => &$value) { 

这使得$value到原来的数组值（而不是复制）的引用。

Answer 2

应该是：

foreach ($arr as $key => $value) { 

    if ($key == 'secondimg') { 
     $arr['secondimg'] = '000'; 

    } 

} 

Answer 3

路过refrence，

$arr = array(); 
$arr['firstimg'] = '123'; 
$arr['secondimg'] = '456'; 
$arr['thirdimg'] = '789'; 

foreach ($arr as $key => $value) { 

    if ($key == 'secondimg') { 
     $value = '000'; 

    } 

} 

print_r($arr); 

到

$arr = array(); 
$arr['firstimg'] = '123'; 
$arr['secondimg'] = '456'; 
$arr['thirdimg'] = '789'; 

foreach ($arr as $key => &$value) { 

    if ($key == 'secondimg') { 
     $value = '000'; 

    } 

} 

print_r($arr);