How to get max element at each index while comparing two arrays?

Question

I have two indexed arrays of identical length:

$first_array = [1,3,4,5,6]; 
$second_array = [5,2,1,7,9];

I need to generate a new array that consists of the higher value between the two elements at each index.

The output should be:

$output_array[5, 3, 4, 7, 9];

Answer 1

Super easy one-liner:

Pass both arrays to array_map(), as it synchronously loops through both sets of data, call max() on the two elements.

Code: (Demo)

$first_array = [1, 3, 4, 5, 6];
$second_array = [5, 2, 1, 7, 9];

var_export(array_map('max', $first_array, $second_array));

Output:

array (
  0 => 5,
  1 => 3,
  2 => 4,
  3 => 7,
  4 => 9,
)