DATE Description and Use

http://msdn.microsoft.com/en-us/library/82ab7w69(VS.71).aspx

This is a 8-byte floating-point number.  Days are represented by whole number increments starting with 30 December 1899.

0.00 is 20 Dec 1899, midnight

-1.00 is 29 December 1899, midnight

5.50 is 4 January 1900, noon.

http://msdn.microsoft.com/en-us/library/k15zsh48.aspx

For comparing two dates:

if ((date2 - date1)  < FLT_EPSILON)

{

      printf("same date");

}

FLT_EPSILON is defined in the LIMITS.H include file for .NET. 

Defined in FLOAT.H for unmanaged code.