Master Essential PHP Array Functions for Cleaner Code

If you want to become a proficient PHP developer, mastering array functions is essential because arrays are used for temporary storage, organization, and processing of data before persisting to a database.

1. array_map

The array_map function applies a given callback to each element of one or more arrays and returns a new array with the results, preserving the original keys.

$numbers = [1, 2, 3, 4];
$squaredNumbers = array_map(
    function($n) {
        return $n * $n;
    },
    $numbers
);
print_r($squaredNumbers);
// Output: [1, 4, 9, 16]

Tip: If you only need to modify the existing array without creating a new one, use array_walk , which applies the callback directly to each element.

2. array_walk

array_walk

applies a callback to each element of an array, modifying the array in place and returning no value.

$numbers = [1, 2, 3, 4];
array_walk($numbers, function(&$n) {
    $n *= $n;
});
print_r($numbers);
// Output: [1, 4, 9, 16]

3. array_reduce

array_reduce

reduces an array to a single value by iteratively applying a callback that receives the accumulated value and the current item.

$numbers = [1, 2, 3, 4];
$sum = array_reduce($numbers, function($carry, $item) {
    return $carry + $item;
}, 0);
echo $sum; // Output: 10

4. array_filter

array_filter

returns a new array containing only the elements for which the callback returns true. The callback can also receive each element's key.

$numbers = [1, 2, 3, 4, 5];
$evenNumbers = array_filter($numbers, function($n) {
    return $n % 2 === 0;
});
print_r($evenNumbers);
// Output: [2, 4]

5. array_merge

array_merge

combines one or more arrays into a single array, overwriting values with the same string keys from later arrays.

$array1 = ["a" => "pomme", "b" => "banane"];
$array2 = ["a" => "ananas", "c" => "citron"];
$result = array_merge($array1, $array2);
print_r($result);
// Output: ["a" => "ananas", "b" => "banane", "c" => "citron"]

6. array_keys

array_keys

returns all the keys of an array. For checking the existence of a specific key, array_key_exists is more direct.

$array = ['nom' => 'Jean', 'âge' => 30];
if (array_key_exists('nom', $array)) {
    echo 'La clé "nom" existe dans le tableau';
}

7. array_values

array_values

returns all the values from an array, re-indexed numerically.

$array = ['a' => 'pomme', 'b' => 'banane', 'c' => 'citron'];
$values = array_values($array);
print_r($values);
// Output: ['pomme', 'banane', 'citron']

8. array_unique

array_unique

removes duplicate values from an array, preserving the first occurrence of each value.

$array = ['pomme', 'banane', 'pomme', 'citron'];
$uniqueArray = array_unique($array);
print_r($uniqueArray);
// Output: ['pomme', 'banane', 'citron']

9. array_combine

array_combine

creates an array by using one array for keys and another for values, useful for pairing related data sets.

$keys = ['nom', 'prénom', 'âge'];
$values = ['Dupont', 'Jean', 30];
$resultat = array_combine($keys, $values);
print_r($resultat);
// Output:
// Array
// (
//     [nom] => Dupont
//     [prénom] => Jean
//     [âge] => 30
// )

Knowing how to manipulate arrays is a fundamental skill for any PHP developer; mastering these functions enables more efficient data handling and cleaner, more maintainable code.