php: datetime() difference between 2 datetime with 2 variables

Question

I have in my database 4 columns which are:

Date_in | Time_in | Date_out | Time_out

Date_in and Time_in belong together (e.g., 2013-02-18 13

Answer 1

// Time format is UNIX timestamp or
// PHP strtotime compatible strings
function dateDiff($time1, $time2, $precision = 6) {
    // If not numeric then convert texts to unix timestamps
    if (!is_int($time1)) {
      $time1 = strtotime($time1);
    }
    if (!is_int($time2)) {
      $time2 = strtotime($time2);
    }

    // If time1 is bigger than time2
    // Then swap time1 and time2
    if ($time1 > $time2) {
      $ttime = $time1;
      $time1 = $time2;
      $time2 = $ttime;
    }

    // Set up intervals and diffs arrays
    $intervals = array('year','month','day','hour','minute','second');
    $diffs = array();

    // Loop thru all intervals
    foreach ($intervals as $interval) {
      // Set default diff to 0
      $diffs[$interval] = 0;
      // Create temp time from time1 and interval
      $ttime = strtotime("+1 " . $interval, $time1);
      // Loop until temp time is smaller than time2
      while ($time2 >= $ttime) {
    $time1 = $ttime;
    $diffs[$interval]++;
    // Create new temp time from time1 and interval
    $ttime = strtotime("+1 " . $interval, $time1);
      }
    }

    $count = 0;
    $times = array();
    // Loop thru all diffs
    foreach ($diffs as $interval => $value) {
      // Break if we have needed precission
      if ($count >= $precision) {
    break;
      }
      // Add value and interval 
      // if value is bigger than 0
      if ($value > 0) {
    // Add s if value is not 1
    if ($value != 1) {
      $interval .= "s";
    }
    // Add value and interval to times array
    $times[] = $value . " " . $interval;
    $count++;
      }
    }

    // Return string with times
    return implode(", ", $times);
}

// Set start & end time
$start_time = "2013-02-18 13:00:00";
$end_time = "2013-02-16 10:00:00";

// Run and print diff
echo dateDiff($start_time, $end_time, 6);

The last argument is the precision.