- floor: documentation ( source)
- gmdate: documentation ( source)
- printf: documentation ( source)
<?php
$seconds_input = (int) 63;
$hours = floor($seconds_input / 3600);
$minutes = floor(($seconds_input / 60) % 60);
$seconds = $seconds_input % 60;
printf("%02d:%02d:%02d", $hours, $minutes, $seconds);
echo "\n";
echo gmdate('H:i:s', $seconds_input);