How to get Windows boot time?

Question

How can I get Windows boot time in C++ with some WinAPI functions? I am currently using the command \"systeminfo\", but I\'m looking for a more proper solution.

Answer 1

I've checked at how Task Manager does it, and turns out it uses the ZwQuerySystemInformation(SystemTimeOfDayInformation, ...) function, which receives the SYSTEM_TIMEOFDAY_INFORMATION structure.

typedef struct _SYSTEM_TIMEOFDAY_INFORMATION {
    LARGE_INTEGER BootTime;
    LARGE_INTEGER CurrentTime;
    LARGE_INTEGER TimeZoneBias;
    ULONG TimeZoneId;
    ULONG Reserved;
    ULONGLONG BootTimeBias;
    ULONGLONG SleepTimeBias;
} SYSTEM_TIMEOFDAY_INFORMATION, *PSYSTEM_TIMEOFDAY_INFORMATION;

(source)

BootTime is what you're looking for.

For something more documented, I think GetTickCount64 will do.