timegm cross platform

Question

I\'m using Visual Studio c++ Compiler ( 2010 ), but the library has different implementation of ANSI C and POSIX libraries function.

What is the difference betw

Answer 1

My implementation of timegm is working on windows.

time_t timegm(struct tm * a_tm)
{
    time_t ltime = mktime(a_tm);
    struct tm tm_val;
    gmtime_s(&tm_val, <ime);
    int offset = (tm_val.tm_hour - a_tm->tm_hour);
    if (offset > 12)
    {
        offset = 24 - offset;
    }
    time_t utc = mktime(a_tm) - offset * 3600;
    return utc;
}

Should be fine.