Trim consecutive duplicate characters

Question

So I'm creating urls for my pages by doing the following:

$uri = strtolower($info->name);
$uri = str_replace('&','and',$uri);

$uri = $info->id."-".preg_replace('/[^a-zA-Z0-9]/','-',$uri);

Basically I make everything lowercase, change & to and and change all special characters to a -. My only problem now if for instance $info->name is this is - a string it will show up as this-is---a-string.

I would like this to become this-is-a-string without doing something like str_replace('---','-',$input);

I figure I need a regular expression for this, but I'm horrible at those so I was wondering if someone can help me out.

Answer 1

Change

$uri = $info->id."-".preg_replace('/[^a-zA-Z0-9]/','-',$uri);

to

$uri = $info->id."-".preg_replace('/[^a-zA-Z0-9]+/','-',$uri);