Convert a time string to an integer.

gistfile1.php

<?php
function string2int($string = "00:00:00") {
  $seconds = 0;
  $string_parts = explode(':', $string);
  $exponent = 0;
  
  while (($timepart = array_pop($string_parts)) !== NULL) {
    $timepart = intval($timepart);
    $seconds += intval($timepart * pow(60, $exponent));
    $exponent++;
  }
  return $seconds;
}