VariantTimeToSystemTime

This function converts the variant representation of time to system time values.

At a Glance

Syntax

HRESULT VariantTimeToSystemTime(double vtime, LPSYSTEMTIME lpSystemTime);

Parameters

vtime

Specifies the variant time that will be converted.

lpSystemTime

Long pointer to the location where the converted time is stored.

Return Values

The return value obtained from the returned INT is one of the following.

Remarks

Passing into this function any invalid and, under some circumstances, NULL pointers will result in unexpected termination of the application.

A variant time is stored as an 8-byte real value (double), representing a date between January 1, 1753 and December 31, 2078, inclusive. The value 2.0 represents January 1, 1900; 3.0 represents January 2, 1900, and so on. Adding 1 to the value increments the date by a day. The fractional part of the value represents the time of day. Therefore, 2.5 represents noon on January 1, 1900; 3.25 represents 6:00 A.M. on January 2, 1900, and so on. Negative numbers represent the dates prior to December 30, 1899.

Using the SYSTEMTIME structure is useful because:

• It spans all time/date periods. MS-DOS date/time is limited to representing only those dates between 1/1/1980 and 12/31/2107.
  
  
• The date/time elements are all easily accessible without needing to do any bit decoding.
  
  
• The National Language Support data and time formatting functions GetDateFormat and GetTimeFormat take a SYSTEMTIME value as input.
  
  
• It is the default Win32 time and date data format supported by Windows NT and Windows 95.