Sos

Please could someone help me out with how to calculate time difference start time and end time using system time automatically. Thats, the start time and end time are used automatically when the person logs in and out respectively using the person's system clock as the inputs. The difference betwen the two times are then calculated and stored/saved in a file located somewhere as log.
This has been giving me too much headaches and would be glad to get over it, code snippets would be very lovely if anyone has any. Best regards to all :)

Sounds like the DateDiff function is what you need.
Use Now to get the system time.

Have two module level variables:

VB Code:

Dim mdLogInTime As Date
Dim mdLogOutTime As Date

When the user logs in:

VB Code:

mdLogInTime = Now

When the user logs out:

VB Code:

mdLogOutTime = Now
 
' To display the time difference in minutes, for example...
MsgBox ("The User was logged in for " & DateDiff("m", mdLogInTime, mdLogOutTime)) & " minutes"

For more info do a search in Help for DateDiff.

Put ur program in the startup entry in the registry.
Then when ur program starts, record the time using
GetTickCount API, and when ur program ends, record the
time again using GetTickCount and calculate the difference.
Caution, though: Be acknowledge who's closing ur program, the
user or the system. This can be done through simple value
checking in ur form_unload or through some APIs.

I would not recommend using DateDiff for what you are looking to do. Experimented with it when writing code for this purpose before and it was completely unreliable [it rounds seconds, minutes, hours very erratically]. So I wrote my own code to calculate time differences which you can find here [go to last posting at this link for the code that eliminates need for a Timer]: http://www.vbforums.com/showthread.php?threadid=245515

What you can do is capture the current system time when the application starts. Then, in the Unload event, capture the current time again, use pieces of the code at the link just provided to calculate the difference in 'start' and 'end' times and then just write all your info to a log file.

If you decide to use GetTickCount you need to be aware that it resets to zero each midnight.

Quote:

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Originally posted by MartinLiss
If you decide to use GetTickCount you need to be aware that it resets to zero each midnight.

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I believe you are thinking of the Timer VB function Marty. GetTickCount starts from when you last restarted the computer.

According to this thread :

From MSDN :

Quote:

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The elapsed time is stored as a DWORD value. Therefore, the time will wrap around to zero if the system is run continuously for 49.7 days.

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[QUOTE]Originally posted by manavo11
From MSDN :

Quote:

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The elapsed time is stored as a DWORD value. Therefore, the time will wrap around to zero if the system is run continuously for 49.7 days. [/Highlight]

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You're right.

Quote:

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Originally posted by MartinLiss
You're right.

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:)

49.7 days? who the hell thought up that number? lol

Take a guess, if you didn't guess a programmer you were unfortunately wrong =(

:p I just want to thank all those that contributed to my "sos" problems I really appreciated ur prompt contributions. Have a lovely week. I will try those suggestions, hopefully they will work out well for me regards all :D