<?php $ar1 = [ 0 => '1-0', 'a' => '1-a', 'b' => '1-b' ]; $ar2 = [ 0 => '2-0', 1 => '2-1', 'b' => '2-b', 'c' => '2-c' ];
Standard input is empty
Array ( [0] => 1-0 [a] => 1-a [b] => 2-b [1] => 2-0 [2] => 2-1 [c] => 2-c ) Array ( [0] => 1-0 [a] => 1-a [b] => 1-b [1] => 2-1 [c] => 2-c )