How Can I Efficiently Flatten Multi-Dimensional Arrays in PHP?

Flattening Multi-Dimensional Arrays in PHP

Many beginners encounter difficulties when attempting to simplify multi-dimensional arrays into a single dimension in PHP. Instead of the complex process of using implode and str_split, there's a more straightforward approach.

Using the call_user_func_array() Function

Combine all elements from the multi-dimensional array using call_user_func_array() with array_merge as the callback function:

$array = [
    [1, 2],
    [3, 4],
    [5, 6],
];

$result = call_user_func_array('array_merge', $array);

// Output: [1, 2, 3, 4, 5, 6]

Recursive Function for Nested Arrays

If your array contains nested arrays, consider using a recursive function:

function array_flatten($array) {
    $return = [];
    foreach ($array as $key => $value) {
        if (is_array($value)) {
            $return = array_merge($return, array_flatten($value));
        } else {
            $return[$key] = $value;
        }
    }
    return $return;
}

$array = [
    [1, [2, 3]],
    [4, [5, 6]],
    [7, [8, 9]],
];

$result = array_flatten($array);

// Output: [1, 2, 3, 4, 5, 6, 7, 8, 9]

Remember, these solutions simplify multi-dimensional arrays into a single dimension. If you require a more complex transformation, further processing may be necessary.

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