- print_r: documentation ( source)
- array_merge: documentation ( source)
- array_keys: documentation ( source)
- array_unique: documentation ( source)
<?php
$array1 = ['code1' => 1, 'code2' => 2];
$array2 = ['code1' => 0, 'code2' => 2, 'code3' => 3];
$all_keys = array_unique(array_merge(array_keys($array1), array_keys($array2)));
$output = array();
foreach ($all_keys as $code) {
$output[$code] = (!empty($array2[$code]) ? $array2[$code] : 0) - (!empty($array1[$code]) ? $array1[$code] : 0);
}
print_r($output);