I use a wrapper around array_merge to deal with SeanWM's comment about null arrays; I also sometimes want to get rid of duplicates. I'm also generally wanting to merge one array into another, as opposed to creating a new array. This ends up as:
/**
* Merge two arrays - but if one is blank or not an array, return the other.
* @param $a array First array, into which the second array will be merged
* @param $b array Second array, with the data to be merged
* @param $unique boolean If true, remove duplicate values before returning
*/
function arrayMerge(&$a, $b, $unique = false) {
if (empty($b)) {
return; // No changes to be made to $a
}
if (empty($a)) {
$a = $b;
return;
}
$a = array_merge($a, $b);
if ($unique) {
$a = array_unique($a);
}
}