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if anyone caould help me with this that would be great im sure it is something simple but for the life of me i cant find out how to do this i have two timestamps and i want to add them together ($timestamp1 + $timestamp2) i have the first part figured out but i cant get the result i want so far i have this 

$flight_time = strtotime($flight_time_1)+strtotime($flight_time_2)+strtotime($flight_time_3)+strtotime($flight_time_4)+strtotime($flight_time_5)+strtotime($flight_time_6)+strtotime($flight_time_7)+strtotime($flight_time_8)+strtotime($flight_time_9)+strtotime($flight_time_10);

$flight_time = date("H:i:s", $flight_time);

and that gives me the time 16:20:00 which is perfect the second code i have is this 

$sqlcow = "SELECT system_flight FROM uav_checks WHERE uav_id = '$registration'";
$result1cow=mysql_query($sqlcow);

while ($arow = mysql_fetch_array($result1cow)){

$system_flight2 = $arow['system_flight'];

}

and with this code i get this 28:07:00 which is perfect

what i need is this 16:20:00 + 28:07:00

however when i try to add them together in every way i know possible it wont work so i am stumped please can anyone help me

thank you

user3744228
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    What is the desired result? – Patrick Q Sep 30 '14 at 14:22
  • You're probably working with **absolute times**, meaning the timestamps have the **year, month and day** information aswell. Thats why it probably doesn't work. – tfrascaroli Sep 30 '14 at 14:25
  • [This question](http://stackoverflow.com/questions/11556731/how-we-can-add-two-date-intervals-in-php) (and the accepted answer) might help. – Patrick Q Sep 30 '14 at 14:28
  • the desired result is a variable that holds the summed total of the two variables $system_flight2 + $flight_time (16:20:00 + 28:07:00) = 44:27:00 – user3744228 Sep 30 '14 at 14:28

2 Answers2

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You're abusing the date/strtotime system in a way it's not intended to be used. e.g.

strtotime('16:20:00') -> 1412115600
date('r', 1412115600) -> Tue, 30 Sep 2014 16:20:20

note how PHP has assumed your "4:20pm" is actually part of "today". It's not "16 hours * 3600 seconds/hour + 20 minutes * 60 seconds/minute" -> 58800 seconds.

strtotime('16:20:00') + strtotime('01:02:30')
1412115600 + 1412060523
2824176123
date('r', 2824176123) -> Sun, 29 Jun 2059 23:22:03

Consider what happens if your time strings add up to more than 24 hours, e.g.

16:20:00 + 7:40:01 -> 23:60:01 -> 1day 00:00:01

Now your H:i:s value will show a time of 00:00:01, which is a very very short flight.

You need to convert your time values to seconds manually, e.g.

(16 * 3600) + (20 * 60) + (0) -> 57600 + 1200 -> 58800
(01 * 3600) + (02 * 60) + (30) -> 3600 + 120 + 30 -> 3750

58800 + 3750 -> 62550

and then back to h:m:s format:

17:22:30
Marc B
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  • Hi i have just tried your way and it works, however i have tried many different ones and they work as well the problem i'm having is exactly as you said i need my time to go higher then 24 hours can you please help me i have converted to seconds and then added them together, and then converted it back it works, however the result i get is along the lines of 00:00:01 not anything higher the 24 – user3744228 Oct 21 '14 at 09:52
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Well sum up timestamp in sql query only as it will be more optimized, convert datetime to unix and then sum all unix timestamps and in php convert to datetime. Please refer to code below.

$sqlcow = "SELECT SUM(UNIX_TIMESTAMP(system_flight)) 
FROM uav_checks WHERE uav_id = '$registration'";
$result1cow=mysql_query($sqlcow);


while ($arow = mysql_fetch_array($result1cow)){

$system_flight2 = $arow['system_flight'];

}

echo gmdate("H:i:s\Z", $system_flight2);
Abhishek Gupta
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