PHP: Convert date to timestamp and back with some format.

<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');

if ( ! function_exists('date_to_unix'))
{
	function date_to_unix($str_date,$format="")
	{
		if (!$str_date) return;
		if (!$format) {
			$CI =& get_instance();
			if (!$format=$CI->config->item('date_format'))
				$format = '%d/%m/%Y %H:%M:%S';
		}
		$timeAr = strptime($str_date, $format);
		return mktime($timeAr["tm_hour"],$timeAr["tm_min"],$timeAr["tm_sec"],$timeAr["tm_mon"]+1,$timeAr["tm_mday"],$timeAr["tm_year"]+1900);
	}
}

if ( ! function_exists('unix_to_date'))
{
	function unix_to_date($time,$format="")
	{
		if (!(int)$time) return;
		if (!$format) {
			$CI =& get_instance();
			if (!$format=$CI->config->item('date_format'))
				$format = '%d/%m/%Y %H:%M:%S';
		}
		
		return strftime($format, $time);
	}
}
?>