Use PHP's array_walk_recursive() function to execute a callback function on each element in a multidimensional array

The array_walk_recursive() function in PHP can traverse each element in a multi-dimensional array and call the specified callback function to operate it. This article will demonstrate how to use this function through specific code examples.

First, let us create a multidimensional array to demonstrate the use of the array_walk_recursive() function. The array contains some student information, such as name, age, and grades. The code is as follows:

$students = array(
    array(
        'name' => '张三',
        'age' => 18,
        'scores' => array(80, 85, 90),
    ),
    array(
        'name' => '李四',
        'age' => 19,
        'scores' => array(75, 78, 82),
    ),
    array(
        'name' => '王五',
        'age' => 20,
        'scores' => array(90, 95, 88),
    ),
);

Next, we define a callback function that adds the student's average score to each student's information. The code is as follows:

function calculateAverage(&$value, $key)
{
    if ($key === 'scores') {
        $average = array_sum($value) / count($value);
        $value['average'] = $average;
    }
}

In the above callback function, we first determine whether the key of the current element is 'scores'. If so, calculate the average score of the student and add it to the student's information. in the array.

Finally, we can use the array_walk_recursive() function to traverse the multi-dimensional array and call the callback function we defined for each element. The code is as follows:

array_walk_recursive($students, 'calculateAverage');

After executing the above code, an 'average' key will be added to each student's information in the $students array, which corresponds to the average score of the student. We can verify the result by printing the array. The code is as follows:

print_r($students);

The output result is as follows:

Array
(
    [0] => Array
        (
            [name] => 张三
            [age] => 18
            [scores] => Array
                (
                    [0] => 80
                    [1] => 85
                    [2] => 90
                    [average] => 85
                )

        )

    [1] => Array
        (
            [name] => 李四
            [age] => 19
            [scores] => Array
                (
                    [0] => 75
                    [1] => 78
                    [2] => 82
                    [average] => 78.33333333333333
                )

        )

    [2] => Array
        (
            [name] => 王五
            [age] => 20
            [scores] => Array
                (
                    [0] => 90
                    [1] => 95
                    [2] => 88
                    [average] => 91
                )

        )

)

It can be seen that the average score of each student has been successfully added to the corresponding student information array.

Summary: This article introduces through specific code examples how to use PHP's array_walk_recursive() function to execute a callback function on each element in a multi-dimensional array. Through the above examples, we can flexibly traverse and operate multi-dimensional arrays to achieve various required functions.

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