我想对此问题提交另一个答案，即AFAICS也处理IDL.

I would like to submit yet another answer to this question, one that AFAICS also deals with the IDL.

此解决方案取决于timegm和mktime.在Windows上，CRT中的timegm作为_mkgmtime可用，换句话说，定义了条件宏.

This solution depends on timegm and mktime. On Windows timegm is available as _mkgmtime from the CRT, in other words define a conditional macro.

#if _WIN32
#    define timegm _mkgmtime
#endif

int local_utc_offset_minutes ( ) {
    time_t t  = time ( NULL );
    struct tm * locg = localtime ( &t );
    struct tm locl;
    memcpy ( &locl, locg, sizeof ( struct tm ) );
    return (int)( timegm ( locg ) - mktime ( &locl ) ) / 60;
}