PHP：如何使用另一个数组中的值覆盖一个数组中的值而不向数组添加新键？

Question

I have an array with default settings, and one array with user-specified settings. I want to merge these two arrays so that the default settings gets overwritten with the user-specified ones.

I have tried to use array_merge , which does the overwriting like I want, but it also adds new settings if the user has specified settings that doesn't exist in the default ones. Is there a better function I can use for this than array_merge ? Or is there a function I can use to filter the user-specified array so that it only contains keys that also exist in the default settings array?

Example of what I want

$default = array('a' => 1, 'b' => 2);
$user = array('b' => 3, 'c' => 4);

// Somehow merge $user into $default so we end up with this:
Array
(
    [a] => 1
    [b] => 3
)

Answer 1

You can actually just add two arrays together ( $user+$default ) instead of using array_merge .

If you want to stop any user settings that don't exist in the defaults you can use array_intersect_key :

Returns an associative array containing all the entries of array1 which have keys that are present in all arguments

Example:

$default = array('a' => 1, 'b' => 2);
$user = array('b' => 3, 'c' => 4);

// add any settings from $default to $user, then select only the keys in both arrays
$settings = array_intersect_key($user + $default, $default);

print_r($settings);

Results:

Array
(
    [b] => 3
    [a] => 1
)

The keys/values (and order) are selected first from $user in the addition, which is why b comes before a in the array, there is no a in $user . Any keys not defined in $user that are defined in $default will then be added to the end of $user . Then you remove any keys in $user + $default that aren't defined in $default .

Answer 2

It's probably simplest to just loop over the keys in the default-settings array, if you only want to consider those. So you can do something like this:

foreach ($default_settings AS $key => $default_value)
{
    if (array_key_exists($key, $user_settings))
    {
        $combined_settings[$key] = $user_settings[$key];
    }
    else
    {
        $combined_settings[$key] = $default_value;
    }
}

Answer 3

foreach($default as $key=>$val){   
  if (isset($user[$key]))
  {
    $settings[$key] = $user[$key];
  } else {
    $settings[$key] = $default[$key];
  } 
}

I think this is what you want.

Answer 4

foreach($user_settings as $key=>$val){   
    $global_settings[$key] = $val; 
}

?