php array merge for associative arrays
<?php
$array1 = array('key1' => 'test1', 'key2' => 'test2');
$array2 = array('key3' => 'test3', 'key4' => 'test4');
$resultArray = array_merge($array1, $array2);
// If you have numeric or numeric like keys, array_merge will
// reset the keys to 0 and start numbering from there
$resultArray = $array1 + $array2;
// Using the addition operator will allow you to preserve your keys,
// however any duplicate keys will be ignored.