Use array_diff_assoc() to determine whether two arrays are exactly equal (value and key)

M66 2025-06-06

How to use array_diff_assoc() to determine whether two arrays are exactly equal in key-value pairs?

In PHP, array comparison is a common operation, especially when we need to determine whether the key-value pairs of two arrays are exactly equal. PHP provides a variety of built-in functions to compare arrays, where the array_diff_assoc() function is particularly suitable for this situation. This article will introduce how to use array_diff_assoc() to determine whether two arrays are exactly equal in key-value pairs.

What is array_diff_assoc() ?

The array_diff_assoc() function is used to compare key-value pairs of two arrays, returning an array containing key-value pairs in the first array but not in the second array. In other words, it checks whether the key names and values of the two arrays are exactly the same and returns the mismatched part.

Function prototype

 array_diff_assoc(array $array1, array $array2): array

Parameter description :

$array1 : The first array.
$array2 : The second array.

Return value :

Returns a new array containing key-value pairs that exist in $array1 but are not in $array2 . If the keys and values of the two arrays exactly match, the result returned will be an empty array.

Use array_diff_assoc() to determine whether the array is completely equal

When we want to determine whether the key-value pairs of two arrays are exactly equal, we can do it in the following ways:

Use array_diff_assoc() to compare two arrays and check if there are different key-value pairs.
If array_diff_assoc() returns an empty array, it means that the key-value pairs of the two arrays are exactly the same.

Sample code

 <?php
// Example array
$array1 = [
    'name' => 'John',
    'age' => 25,
    'email' => 'john@example.com',
];

$array2 = [
    'name' => 'John',
    'age' => 25,
    'email' => 'john@m66.net',
];

// use array_diff_assoc Compare arrays
$result = array_diff_assoc($array1, $array2);

// Determine whether two arrays are exactly equal
if (empty($result)) {
    echo "Two arrays are exactly equal in key-value pairs。\n";
} else {
    echo "Two arrays have unequal parts on key-value pairs：\n";
    print_r($result);
}
?>

Code parsing :

We define two arrays $array1 and $array2 , where the value of the email key of $array2 is different from $array1 .
Use array_diff_assoc($array1, $array2) to compare these two arrays. Because the email key values are different, the function returns an array containing unequal parts.
If the return result is empty, it means that the two arrays are exactly equal on key-value pairs. Otherwise, we can view the returned results and find out the differences.

Sample output

 Two arrays have unequal parts on key-value pairs：
Array
(
    [email] => john@example.com
)

Why use array_diff_assoc() ?

When array_diff_assoc() compares arrays, not only will the keys of the array be compared, but the values corresponding to each key are also compared. In this way, it can accurately determine whether the two arrays are completely equal, avoiding the potential problems caused by simply using the == or === operator. It is a very practical array comparison tool, especially when it is necessary to accurately compare two arrays.

summary

By using the array_diff_assoc() function, PHP developers can easily judge the difference between two arrays in key-value pairs. If the returned empty array, the two arrays are exactly equal on key-value pairs. If the returned result contains key-value pairs, it means that there is a difference between the two arrays. In practical applications, this function is very suitable for data verification, configuration checking and other scenarios.

array_diff_assoc