- preg_match_all: documentation ( source)
- implode: documentation ( source)
- explode: documentation ( source)
<?php
$file = "holm_25-747.jpg";
$findnum = explode("-",$file);
preg_match_all('/([\d]+)/', $findnum[0], $match);
$sortnum = implode("", $match[0]);
echo $sortnum;