Here are two excerpts from the Windows SDK help files for timeGetTime and QueryPerformanceCounter API functions.
timeGetTime
The timeGetTime function retrieves the system time, in milliseconds. The system time is the time elapsed since Windows was started.
DWORD timeGetTime(VOID);
Parameters
This function does not take parameters.
Return Values
Returns the system time, in milliseconds.
Remarks
The only difference between this function and the timeGetSystemTime function is that timeGetSystemTime uses the MMTIME structure to return the system time. The timeGetTime function has less overhead than timeGetSystemTime.
Note that the value returned by the timeGetTime function is a DWORD value. The return value wraps around to 0 every 2^32 milliseconds, which is about 49.71 days.This can cause problems in code that directly uses the timeGetTime return value in computations, particularly where the value is used to control code execution. You should always use the difference between two timeGetTime return values in computations.
Windows NT: The default precision of the timeGetTime function can be five milliseconds or more, depending on the machine. You can use the timeBeginPeriod and timeEndPeriod functions to increase the precision of timeGetTime. If you do so, the minimum difference between successive values returned by timeGetTime can be as large as the minimum period value set using timeBeginPeriod and timeEndPeriod. Use the QueryPerformanceCounter and QueryPerformanceFrequency functions to measure short time intervals at a high resolution,
Windows 95: The default precision of the timeGetTime function is 1 millisecond. In other words, the timeGetTime function can return successive values that differ by just 1 millisecond. This is true no matter what calls have been made to the timeBeginPeriod and timeEndPeriod functions.
See Also
timeGetSystemTime, MMTIME, timeGetTime, timeBeginPeriod, timeEndPeriod, QueryPerformanceCounter, QueryPerformanceFrequency
QueryPerformanceCounter
The QueryPerformanceCounter function retrieves the current value of the high-resolution performance counter, if one exists.
BOOL QueryPerformanceCounter(
LARGE_INTEGER *lpPerformanceCount // address of current counter value
);
Parameters
lpPerformanceCount
Points to a variable that the function sets, in counts, to the current performance-counter value. If the installed hardware does not support a high-resolution performance counter, this parameter can be to zero.
Return Values
If the installed hardware supports a high-resolution performance counter, the return value is nonzero.
If the installed hardware does not support a high-resolution performance counter, the return value is zero.
See Also
QueryPerformanceFrequency
