Math with time

acey99

anybody know where I can get some documentation on how to to math with time ??

toma42

math with time is simplistic if you use the unix timestamp.

You can convert a date to a timestamp using strtodate() and you can get the current timestamp using time()

a time stamp is the number of seconds since the unix epoch.

Example: If you want the number of days between 1/1/2002 and 4/2/2002:
$daysbetween = (strtodate('04/02/2002') - strtodate('01/01/2002') ) / 86400;

there are 86400 seconds in a day, hence the division to get # of days.

acey99

yeah, but what about things like 10:00a - 9:30a (or in 24hr format) : 1000-0930

it reaches a value of 70

I'm looking for a formula (or road to take) to calculate things like this...

acey99

figured out my own problem.

Solution for those who want to know...

best way to do this is in seconds.

you take the number of seconds at start subtract it from the number of seconds at end eg:
endseconds-startseconds

then depending on how you want it divded up (I Did Quarter hours)

you get :

if ($ans >= 900) { # each 1/4 hr
while($ans >= 900) {
$hrs++; # increment hours
$ans-=900; # decrement by 1/4 hour
}
$hrs/=4; # 1/4 of hour
$ans=$hrs;
}

/*
Seconds =

300 = 5 minutes / ?? hr
900 = .25 hr / 15 minutes
1800 = .5 hr/30 minutes
3600 = 1 hr/60 minutes
4500 = 1.25 hrs
5400 = 1.5 hr
6300 = 1.75 hrs
7200 = 2 hrs
9000 = 2.5
10800 = 3 hrs
12600 = 3.5
14400 = 4 hrs
...
28800 = 8 hrs
...
57600 = 16 hrs
...
86400 = 24 hrs (1 day)
...

*/