11 25 2008
PHP tip: Use a regular expression in a switch statement
I came across this nugget while trying to rapidly prototype some new functionality for one of my clients. The client wanted specific artwork to show up for a subset of related items. The prototype has worked out so well, that I haven't yet had to go back add a flag field to the underlying database table. One of the things I had going for me was that the SKUs I needed to identify followed a rigid naming convention. I didn't want to update the switch statement each time a new SKU is added, so instead of this:
switch($sku) {
case '11012E':
case '11345E':
case '11678E':
case '11901E':
// ... do stuff
break;
case '08012E':
case '08345E':
// ... do different stuff
break;
}
You can use a function in a switch statement to return the result of a regular expression. Even better.
switch($sku) {
case (preg_match("/^11[0-9]{3}E$/i", $sku) ? $sku : !$sku):
// ... do stuff
break;
case (preg_match("/^08[0-9]{3}E$/i", $sku) ? $sku : !$sku):
// ... do different stuff
break;
}
What others are saying...
TRUE, and use the fall through to grant access in a hierarchy without repeating your code for each role and avoiding a nasty if block.switch(TRUE) { case $user->is_superuser(): $access['manage_users'] = TRUE; $access['write_posts'] = TRUE; case $user->is_admin(): $access['moderate_comments'] = TRUE; $access['moderate_categories'] = TRUE; case $user->is_member(): $access['write_comments'] = TRUE; default: $access['view_posts'] = TRUE; break; }