Time calculation am pm problem

[kartik]

Dialogue form.
I have two text boxes (shorttime). starttime and endtime.
The user gets a drop down of the current time with am and pm (and user can change it).
I find the calculation of hours is giving me strange result.
starttime 08:30 AM
endtime 02:30 PM
MY CALCULATION: endtime - starttime and I get minus numbers.
ROUND(((endtime-starttime)/3600),2)
Is there a function to convert endtime to 24hour format? In this way my calculation will not result in negative.
How do I round the hours and min to nearst 15 min.
I tried to use round function and I am not sure about nearest 15 min rounding function.

[Davidk]

Re: Time calculation am pm problem

This can be done fairly simply, if you have some other stuff available. Do you also have the date for each of the start and end times?

[kartik]

Re: Time calculation am pm problem

No. Just start time and end time. They are shorttime fields. User enters the short time using drop down (similar to date).
The drop down time shows the current time with am / pm. User changes it as needed.

[Davidk]

Re: Time calculation am pm problem

So... if no dates then I'm gonna take a guess and say that the times are within the same day... so that's good. I believe the reason the calc is troublesome is that javascript likes to have a full date to work with... time and date. You don't say how you're doing the calculation, but in javascript try something like this...

var startTime = new Date({dialog.Object}.getValue('startTime') + '1/1/1900');
var endTime = new Date({dialog.Object}.getValue('endTime') + '1/1/1900');

var diffTime = endTime - startTime;
alert(startTime + ' ' + endTime + ' ' + diffTime);

Append a date to the end of your time, and perform the calc.

[madtowng]

Re: Time calculation am pm problem

Hi Kartik,

I put my basic answer into in big picture. It shows the dialog with data and results, the code in the on_change event, and the basic setup of the dialog.
I might be able to help with the 15 minute rounding, but really need to know how exact you want it to be.

Hope this helps,

Gregg

[madtowng]

Re: Time calculation am pm problem

Just gotta love things that stick in your head.
It's easier to share a sample dialog than describe everything without it.

I find it is much easier to manipulate time using xbasic than javascript.

[Davidk]

Re: Time calculation am pm problem

Here's a bit more for the 15 minute rounding...

Thanks to MIC at StackOverflow for the function.

var startTime = new Date({dialog.Object}.getValue('startTime') + '1/1/1900');
var endTime = new Date({dialog.Object}.getValue('endTime') + '1/1/1900');

var milliseconds = endTime - startTime;

var hrsMins = dhm(milliseconds);

alert(hrsMins);

function dhm(t){
    var cd = 24 * 60 * 60 * 1000,
        ch = 60 * 60 * 1000,
        days = Math.floor(t / cd),
        hrs = Math.floor( (t - days * cd) / ch),
        mins = Math.round( (t - days * cd - hrs * ch) / 60000),
		m = (Math.round(mins/15) * 15) % 60,
		h = mins > 52 ? ++hrs : hrs;        
        return [h, m].join(':');
}

I agree that performing some of this stuff is easier in Xbasic. With Javascript you pretty much have to pull dates and times apart just to work with them... and then you have to put them back together. However... build a few functions and they're always there for you... and no going back to the server. I'd rather have a few more lines of client code than go back to the server.