| Microsoft Office 2000/Visual Basic Programmer's Guide | |
VBA provides the Date data type to store date and time values. The Date data type is an 8-byte floating-point value, so internally it's the same as the Double data type. The Date data type can store dates between January 1, 100, and January 1, 9999.
VBA stores the date value in the integer portion of the Date data type, and the time value in the decimal portion. The integer portion represents the number of days since December 30, 1899, which is the starting point for the Date data type. Any dates before this one are stored as negative numbers; all dates after are stored as positive values. If you convert a date value representing December 30, 1899, to a double, you'll find that this date is represented by zero.
The decimal portion of a date represents the amount of time that has passed since midnight. For example, if the decimal portion of a date value is .75, three-quarters of the day has passed, and the time is now 6 P.M.
Because the integer portion of a date represents number of days, you can add and subtract days from one date to get another date.