PHP，将gmdate添加到gmdate

I have a code that looks like this:

        $dagtidhelg = gmdate('H:i', $diffMorning) . "
";
        $kvallstidhelg = gmdate('H:i', $diffNight);

This code runs several times per page since its runt every time a row is loaded from mysql. It can return a time value ie 08:15 and 09:30. This is the lenght of two work sessions.

That works great but now Im stuck, I want to display the total of every work session at the bottom. I have tried this:

        $dagtidhelgtotal = $dagtidhelgtotal + $dagtidhelg;
        $kvalltidhelgtotal = $kvalltidhelgtotal + $kvallstidhelg;

But that only adds the hours togheter, it wont even display the : So Im guessing that Im doing this totaly wrong.

How can I add these times togheter? Maybe convert them to minutes, then add them all togheter?

Add duration together is simple .But you must keep in mind that duration and date are two things completely different. You can write 100:08 for duration but not for date. If your purpose is to keep a duration counter on(one or) every page(s) you need to build a system based on $_SESSION variable. To add two duree you can proceed like this:

function addDuration($duration1,$duration2){

        $result=array_map(function($x,$y){return sprintf("%'.02d", $x+$y);},explode(':',$duration1),explode(':',$duration2));
        if($result[1]>60){
            $result[0]=sprintf("%'.02d",$result[0]+(int)$result[1]/60);
            $result[1]=sprintf("%'.02d",$result[1]%60);
        }elseif($result[1]==60){
            $result[1]="00";
            $result[0]=sprintf("%'.02d",$result[0]+1);
        }
        return  join(':',$result);
}

and the usage in your case could be:

 $dagtidhelgtotal = addDuration($dagtidhelgtotal,$dagtidhelg);

if we suppose that

$dagtidhelgtotal ==='100:09' && $dagtidhelg === '08:08'

then after the addition $dagtidhelgtotal will be equal to '108:17';