What does array_merge() do?

The function array_merge() is specifically designed to combine two or more arrays into a single array. When using array_merge(), the elements of the arrays passed to it will be merged together sequentially. If the arrays contain numeric keys, the actual values will be renumbered from zero, while if associative keys are present, those keys will be preserved.

For example, if you have two arrays:

$array1 = ['a' => 'apple', 'b' => 'banana'];
$array2 = ['c' => 'cherry', 'd' => 'date'];
$result = array_merge($array1, $array2);

The resulting array will be:

Array
(
    [a] => apple
    [b] => banana
    [c] => cherry
    [d] => date
)

This illustrates how array_merge() effectively combines different arrays into a single array that maintains all elements from the original arrays. The behavior of renumbering numeric keys and preserving associative keys makes it a useful function for various tasks in PHP that require combining array data.