getTimeDiff

function getTimeDiff($timestamp=false) {
 
	$current_time = time();
 
	if ($timestamp) {
 
		// Determine the difference, between the time now and the timestamp
		$difference = $current_time - $timestamp;
 
   		// Set the periods of time
  		$periods = array("second", "minute", "hour", "day", "week", "month", "year", "decade");
		$lengths = array(1, 60, 3600, 86400, 604800, 2630880, 31570560, 315705600);
 
   		// Determine which period we should use, based on the number of seconds lapsed.
   		// If the difference divided by the seconds is more than 1, we use that.
  	 	// Go from decades backwards to seconds       
   		for (
			$val = sizeof($lengths) - 1; 
			($val >= 0) && (($number = $difference / $lengths[$val]) <= 1);
			$val--
		);
 
   		// Ensure the script has found a match
   		if ($val < 0) $val = 0;
 
   		// Determine the minor value, to recurse through
   		$new_time = $current_time - ($difference % $lengths[$val]);
 
   		// Set the current value to be floored
   		$number = floor($number);
 
   		// If required create a plural
   		if ($number != 1) $periods[$val] .= "s";
 
   		// Return text
   		$text = sprintf("%d %s ", $number, $periods[$val]);   
 
   		return $text;
	}
}