Opposite of DateAdd

[Excel Fox]

Rasm, I do not intend to question the sanctity of the theories in that site, however, I know for sure that if you convert a date time value in Excel to its value, the number returned will be equivalent to the number of days starting from 1/1/1900 0:00:00, inclusive of all leap years and leap seconds.

So based on my theory, 10/27/2011 12:01:51 AM will be converted to 40843.00128 (days) which means 40843.00128*3600*24 seconds = 3528835311 seconds

Now, if you reverse this to date, using a simple text function like so =TEXT(D1,"m/d/yyyy h:mm:ss AM/PM"), you would get the original date 10/27/2011 12:01:51 AM

If you are still confused, I can prove it with an attachment

[Rasm]

You are absolutely correct - however I am reading my date stamps as long integers from a Binary file - using random access -- along with a bunch more info - next I manipulate my data in Excel - next I write back to the binary file - But now have to leave a date/time stamp of my modification. So this is where I need to convert the Date/time stamp into a long integer. The binary files are originally written by C++ code.

So the example you shown me above - I will use that - all I have to do is subtract an offset in seconds to represent thetime period 1900 to 1980.

So this I will test - thank you very much.