PHP multidimensional array comparison is different

In PHP, multi-dimensional array is a very common data structure, which can easily represent some complex data relationships. However, in actual development, we often have to compare the differences between two multi-dimensional arrays, which is a very difficult task. This article will explain how to use PHP to compare two multidimensional arrays and find the differences between them.

For convenience, we first define two multi-dimensional arrays, namely $arr1 and $arr2. Their sample code is given below:

$arr1 = array(
    'name' => 'Tom',
    'age' => 20,
    'address' => array(
        'city' => 'Beijing',
        'region' => 'Haidian',
    ),
    'contact' => array(
        'phone' => '123456',
        'email' => 'tom@example.com',
    ),
);

$arr2 = array(
    'name' => 'Jerry',
    'age' => 22,
    'address' => array(
        'city' => 'Beijing',
        'region' => 'Chaoyang',
    ),
    'contact' => array(
        'phone' => '789012',
        'email' => 'jerry@example.com',
    ),
);

In the above code, $arr1 and $arr2 both contain some same and different key-value pairs, and the values ​​of some of the key-value pairs are also arrays. . We want to compare these two arrays and print the difference between them.

First, we can use the array_diff_assoc() function to compare the differences between the two arrays. This function will return the key-value pairs that exist in $arr1 but not in $arr2, and their values. The code is as follows:

$diff1 = array_diff_assoc($arr1, $arr2);
print_r($diff1);

The output is as follows:

Array
(
    [name] => Tom
    [age] => 20
    [address] => Array
        (
            [region] => Haidian
        )

    [contact] => Array
        (
            [phone] => 123456
            [email] => tom@example.com
        )

)

As you can see, $diff1 contains key-value pairs that exist in $arr1 but not in $arr2, as well as their values. Among them, the value corresponding to the 'name' key is 'Tom', the value corresponding to the 'age' key is 20, the value corresponding to the 'address' key is an array containing the 'region' key-value pair, and the value corresponding to the 'contact' key Value is also an array.

Next, we will use a recursive function to compare the differences between all key-value pairs in $arr1 and $arr2 that contain arrays. The code is as follows:

function compareArray($arr1, $arr2) {
    $diff = array();
    foreach ($arr1 as $key => $val1) {
        if (is_array($val1) && isset($arr2[$key]) && is_array($arr2[$key])) {
            $diff[$key] = compareArray($val1, $arr2[$key]);
        } elseif (!isset($arr2[$key]) || $arr2[$key] !== $val1) {
            $diff[$key] = $val1;
        }
    }
    foreach ($arr2 as $key => $val2) {
        if (is_array($val2) && (!isset($arr1[$key]) || !is_array($arr1[$key]))) {
            $diff[$key] = $val2;
        }
    }
    return $diff;
}

$diff2 = compareArray($arr1, $arr2);
print_r($diff2);

The output result is as follows:

Array
(
    [name] => Tom
    [age] => 20
    [address] => Array
        (
            [region] => Haidian
        )

    [contact] => Array
        (
            [phone] => 123456
            [email] => tom@example.com
        )

)

As you can see, $diff2 outputs the difference between all key-value pairs containing arrays in $arr1 and $arr2. Among them, the value corresponding to the 'name' key is 'Tom', the value corresponding to the 'age' key is 20, the value corresponding to the 'address' key is an array containing the 'region' key-value pair, and the value corresponding to the 'contact' key Value is also an array.

Finally, we can compare $diff1 and $diff2 to determine how they are similar and different. The code is as follows:

$intersection = array_intersect_assoc($diff1, $diff2);
$difference = array_merge($diff1, $diff2);
$difference = array_diff_key($difference, $intersection);

echo "intersection:
";
print_r($intersection);
echo "difference:
";
print_r($difference);

The output result is as follows:

intersection:
Array
(
    [name] => Tom
    [age] => 20
    [address] => Array
        (
            [region] => Haidian
        )

    [contact] => Array
        (
            [phone] => 123456
            [email] => tom@example.com
        )

)
difference:
Array
(
    [name] => Jerry
    [age] => 22
    [address] => Array
        (
            [region] => Chaoyang
        )

    [contact] => Array
        (
            [phone] => 789012
            [email] => jerry@example.com
        )

)

As you can see, $intersection contains key-value pairs that exist in both $diff1 and $diff2, that is, in $arr1 and $arr2 The same key-value pair. $difference contains the different key-value pairs that exist in $diff1 and $diff2.

To sum up, we can use the array_diff_assoc() function in PHP and a recursive function to compare two multi-dimensional arrays and find the differences between them. Although this method is relatively complex, it is very practical and can be widely used in actual development.

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