I have the string "Hello_+ Wo--rld" which I'm trying to replace double dashes however when an instance of "_+" is encountered it replaces it with two dashes. If I remove the plus sign from $d then it won't replace double dashes with single dashes. The only work-around I've been able to get to work is using a second $d regular expression however I'd really like to avoid that. Suggestions please?

- John

<?php
$a = strtolower(Hello_+ Wo--rld");

$b = str_ireplace('_','-',$a);

$c = str_ireplace(' ','-',$b);

$d = preg_replace('/[--]+/','-',$c);

$e = preg_replace('/[^a-z0-9-]/','',$d);

$f = trim($e,'-');

echo $f;
?>