Time Functions

The following functions are used with system time.

Function	Description
GetSystemTime	Retrieves the current system date and time in UTC format.
GetSystemTimeAdjustment	Determines whether the system is applying periodic time adjustments to its time-of-day clock.
GetTimeFormat	Formats a system time as a time string for a specified locale.
NtQuerySystemTime	Returns the system time.
RtlLocalTimeToSystemTime	Converts the specified local time to system time.
RtlTimeToSecondsSince1970	Converts the specified system time to the number of seconds since the first second of January 1, 1970.
SetSystemTime	Sets the current system time and date.
SetSystemTimeAdjustment	Enables or disables periodic time adjustments to the system's time-of-day clock.
SystemTimeToFileTime	Converts a system time to a file time.
SystemTimeToTzSpecificLocalTime	Converts a UTC time to a specified time zone's corresponding local time.
TzSpecificLocalTimeToSystemTime	Converts a local time to a UTC time.

 

The following functions are used with local time.

Function	Description
EnumDynamicTimeZoneInformation	Enumerates dynamic daylight saving time information entries stored in the registry.
FileTimeToLocalFileTime	Converts a UTC file time to a local file time.
GetDynamicTimeZoneInformation	Retrieves the current time zone and dynamic daylight saving time settings.
GetDynamicTimeZoneInformationEffectiveYears	Retrieves a range, expressed in years, for which a DYNAMIC_TIME_ZONE_INFORMATION has valid entries.
GetLocalTime	Retrieves the current local date and time.
GetTimeZoneInformation	Retrieves the current time zone settings.
GetTimeZoneInformationForYear	Retrieves the time zone settings for the specified year and time zone.
RtlLocalTimeToSystemTime	Converts the specified local time to system time.
SetDynamicTimeZoneInformation	Sets the current time zone and dynamic daylight saving time settings.
SetLocalTime	Sets the current local time and date.
SetTimeZoneInformation	Sets the current time zone settings.
SystemTimeToTzSpecificLocalTime	Converts a UTC time to a specified time zone's corresponding local time.
SystemTimeToTzSpecificLocalTimeEx	Converts a UTC time with dynamic daylight saving time settings to a specified time zone's corresponding local time.
TzSpecificLocalTimeToSystemTime	Converts a local time to a UTC time.
TzSpecificLocalTimeToSystemTimeEx	Converts a local time with dynamic daylight saving time settings to UTC time.

 

The following functions are used with file time.

Function	Description
CompareFileTime	Compares two file times.
FileTimeToLocalFileTime	Converts a UTC file time to a local file time.
FileTimeToSystemTime	Converts a file time to system time format.
GetFileTime	Retrieves the date and time that the specified file or directory was created, last accessed, and last modified.
GetSystemTimeAsFileTime	Retrieves the current system date and time in UTC format.
LocalFileTimeToFileTime	Converts a local file time to a file time based on UTC.
SetFileTime	Sets the date and time that the specified file or directory was created, last accessed, or last modified.
SystemTimeToFileTime	Converts a system time to a file time.

 

The following functions are used with MS-DOS date and time.

Function	Description
DosDateTimeToFileTime	Converts MS-DOS date and time values to a file time.
FileTimeToDosDateTime	Converts a file time to MS-DOS date and time values.

 

The following functions are used with Windows time.

Function	Description
GetSystemTimes	Retrieves system timing information.
GetTickCount	Retrieves the number of milliseconds that have elapsed since the system was started, up to 49.7 days.
GetTickCount64	Retrieves the number of milliseconds that have elapsed since the system was started.

 

The following functions are used with high-resolution performance counters.

Function	Description
QueryPerformanceCounter	Retrieves the current value of the high-resolution performance counter.
QueryPerformanceFrequency	Retrieves the frequency of the high-resolution performance counter.

 

The following functions are used with the auxiliary performance counter.

Function	Description
QueryAuxiliaryCounterFrequency	Queries the auxiliary counter frequency.
ConvertAuxiliaryCounterToPerformanceCounter	Converts the specified auxiliary counter value to the corresponding performance counter value; optionally provides the estimated conversion error in nanoseconds due to latencies and maximum possible drift.
ConvertPerformanceCounterToAuxiliaryCounter	Converts the specified performance counter value to the corresponding auxiliary counter value; optionally provides the estimated conversion error in nanoseconds due to latencies and maximum possible drift.

 

The following function is used with interrupt time.

Function	Description
QueryInterruptTime	Gets the current interrupt-time count.
QueryInterruptTimePrecise	Gets the current interrupt-time count, in a more precise form than QueryInterruptTime does.
QueryUnbiasedInterruptTime	Gets the current unbiased interrupt-time count. The unbiased interrupt-time count does not include time the system spends in sleep or hibernation.
QueryUnbiasedInterruptTimePrecise	Gets the current unbiased interrupt-time count, in a more precise form than QueryUnbiasedInterruptTime does. The unbiased interrupt-time count does not include time the system spends in sleep or hibernation.