English
English
In PHP, array_diff_key() and array_diff_assoc() are both functions used to compare arrays, but their comparison methods are obviously different from those applicable scenarios. This article will explain the differences between these two functions in detail and discuss their respective usage scenarios.
array_diff_key() is used to compare the key names (keys) of two or more arrays and returns those key-value pairs that exist in the first array but not in other arrays.
array_diff_key(array $array1, array $array2, array ...$arrays): array
$array1 : The first array (reference array).
$array2, ...$arrays : The array to be compared with the first array.
$array1 = [
"a" => 1,
"b" => 2,
"c" => 3
];
$array2 = [
"a" => 4,
"c" => 5
];
$result = array_diff_key($array1, $array2);
print_r($result);
Array
(
[b] => 2
)
In this example, array_diff_key() compares the key names of two arrays. The results returned are those key-value pairs that are in $array1 but not in $array2 .
array_diff_assoc() is used to compare key names and values (key and value) of two or more arrays, returning key-value pairs that exist in the first array but not in other arrays. Unlike array_diff_key() , it not only compares the key names, but also compares the values corresponding to the keys.
array_diff_assoc(array $array1, array $array2, array ...$arrays): array
$array1 : The first array (reference array).
$array2, ...$arrays : The array to be compared with the first array.
$array1 = [
"a" => 1,
"b" => 2,
"c" => 3
];
$array2 = [
"a" => 4,
"c" => 3
];
$result = array_diff_assoc($array1, $array2);
print_r($result);
Array
(
[a] => 1
[b] => 2
)
In this example, array_diff_assoc() compares the key names and values of $array1 and $array2 . The results returned are those key-value pairs that have in $array1 but do not have the exact same key name and value in $array2 .
array_diff_key() only compares the key names and ignores the corresponding values of the key.
array_diff_assoc() compares key names and values at the same time. Only when the key names and values are different will it be considered different.
array_diff_key() is suitable for scenarios where you only care about the key names of the array, but not the corresponding values. For example, you want to remove certain keys, or compare the structure of two arrays.
array_diff_assoc() is suitable for common scenarios when you need to completely compare keys and values in an array, such as filtering out elements with different key names and values in two arrays.
Suppose we have an array that contains different URLs and needs to be replaced. We can use array_diff_key() or array_diff_assoc() to implement replacement, depending on whether we need to compare based on key or key value.
$urls = [
"home" => "http://m66.net/home",
"about" => "http://example.com/about",
"contact" => "http://m66.net/contact"
];
$other_urls = [
"home" => "http://m66.net/home",
"about" => "http://m66.net/about",
];
$result = array_diff_key($urls, $other_urls);
print_r($result);
Array
(
[contact] => http://m66.net/contact
)
In this example, we compare only based on the key name and finally find the items that are in $urls but not in $other_urls .
The above is the difference between array_diff_key() and array_diff_assoc() . According to your needs, choosing the right function to handle array differences can effectively improve the efficiency and readability of the code.
