Converting SYSTEMTIME to time_t?

[danielmccarthy]

I am having trouble converting SYSTEMTIME to time_t

Can anyone help me with this situation please?

[Peter87]

Not sure if there is another way but you could probably use std::mktime.
http://en.cppreference.com/w/cpp/chrono/c/mktime

[danielmccarthy]

bump -

[danielmccarthy]

bump --

[Peter87]

I meant something like this:

#include <ctime>

int main()
{
	SYSTEMTIME st;
	std::tm tm;
	
	tm.tm_sec = st.wSecond;
	tm.tm_min = st.wMinute;
	tm.tm_hour = st.wHour;
	tm.tm_mday = st.wDay;
	tm.tm_mon = st.wMonth - 1;
	tm.tm_year = st.wYear - 1900;
	tm.tm_isdst = -1;
	
	std::time_t t = std::mktime(&tm);
}

[danielmccarthy]

Thanks for your reply, mktime returns -1 with that code

[Peter87]

Did you use a valid SYSTEMTIME?

[danielmccarthy]

yeah its from the calendar component

[danielmccarthy]

Sorry mate it was the wrong SYSTEMTIME after that. I think I been working too long lol break for me. It works brilliantly thanks mate. Could you explain to me why you have to minus 1900 and 1 from the month?

[Peter87]

It's just that they store some of the data differently. SYSTEMTIME stores the month as a number from 1 to 12 while std::tm stores it as a number from 0 to 11. SYSTEMTIME stores the year like you would expect (starting from 0) but std::tm stores it as the number of years since 1900.

You can compare them for yourself if you want:
http://en.cppreference.com/w/cpp/chrono/c/tm
http://msdn.microsoft.com/en-us/library/windows/desktop/ms724950.aspx

[danielmccarthy]

thanks