Is there a php function or more efficient way to add two iso 8601 times together?

Question

I could not find a method to help me do the following. I am given the following two time values: PT1H30M and PT1H45M. My goal is to add the two time values together to get PT2H5M.

Are there any functions or a more efficient way to write this?

This is what I did for each of the arguments that was passed through:

Remove PT from the time value.
Extract ??H and ??M into separate variables.
Removed H and M from those variables and made sure the remaining values is of int type.
Added the two hour values together as well as the two minute values.
If the sum of minutes exceeded 59 it is broken down and added to the hours.
The results is returned as the sum of the two time values.

Here is my code sample:

//* _h is short for hours and _m is short for minutes
function iso8601TimeSum($t1 = '', $t2 = '') {
    if(!$t1 && !$t2)
        return '';

    //remove PT 
    $t1 = str_replace('PT', '', $t1);
    $t2 = str_replace('PT', '', $t2);

    //extract ??[H|h] and ??[M|m] 
    $t1h_found = preg_match('/[00-59][Hh]/i', $t1, $t1_h);
    $t1m_found = preg_match('/[00-59][Mm]/i', $t1, $t1_m);
    $t2h_found = preg_match('/[00-59][Hh]/i', $t2, $t2_h);
    $t2m_found = preg_match('/[00-59][Mm]/i', $t2, $t2_m);

    //remove H|h and M|m from extracted values
    if($t1h_found)
        $t1_h = intval(preg_replace('/[Hh]/i', '', $t1_h[0]));

    if($t1m_found)
        $t1_m = intval(preg_replace('/[Mm]/i', '', $t1_m[0]));

    if($t2h_found)
        $t2_h = intval(preg_replace('/[Hh]/i', '', $t2_h[0]));

    if($t2m_found)
        $t2_m = intval(preg_replace('/[Mm]/i', '', $t2_m[0]));

    //add it together
    $calc_t_h = (!empty($t1_h) ? $t1_h : 0) + (!empty($t2_h) ? $t2_h : 0);
    $calc_t_m = (!empty($t1_m) ? $t1_m : 0) + (!empty($t2_m) ? $t2_m : 0);

    //if minutes exceeds 59 break it down and add it to the hours.
    if($calc_t_m > 59) {
        $calc_t_h += round($calc_t_m / 60);
        $calc_t_m = $calc_t_m % 60;
    }

    return 'PT' . ($calc_t_h > 0 ? $calc_t_h . 'H' : '00H') . ($calc_t_m > 0 ? $calc_t_m . 'M' : '00M');
}

var_dump(iso8601TimeSum('PT1H30M', 'PT1H45M'));
//*/

Those are [`DateInterval`](http://php.net/manual/class.dateinterval.php) strings, not *"time values"* — Phil, Apr 10 '15 at 06:36

score 0 · Accepted Answer · answered Apr 10 '15 at 06:40

You should use DateTime objects, there are handy functions that parse dates based on format: check http://php.net/manual/en/datetime.createfromformat.php

DateTime objects can also be used with math operations. I personally use this wrapper: https://github.com/briannesbitt/Carbon

Implementing your logic will be significanlty easier then

Is there a php function or more efficient way to add two iso 8601 times together?

1 Answers1