[Windows] Local time 轉 UTC

Window提供了 API 可以轉換時間的時區。

• TzSpecificLocalTimeToSystemTime：Local time -> UTC
• SystemTimeToTzSpecificLocalTime ：UTC -> Local time

第一個參數可指定 TIME_ZONE_INFORMATION，如果傳進 NULL 的話，即代表目前系統使用的Time Zone。

SYSTEMTIME ConvertLocalTime2UTC(UINT year, UINT month, UINT day, UINT hour, UINT minute, UINT second)
{
    SYSTEMTIME local, utc;
    ZeroMemory(&local, sizeof(local));
    local.wYear   = year;
    local.wMonth  = month;
    local.wDay    = day;
    local.wHour   = hour;
    local.wMinute = minute;
    local.wSecond = second;
    TzSpecificLocalTimeToSystemTime( NULL, &local, &utc );
    printf("UTC Time  =%d/%d/%d %d:%d:%d\n", utc.wYear, utc.wMonth, utc.wDay, utc.wHour, utc.wMinute, utc.wSecond);
    printf("Local Time=%d/%d/%d %d:%d:%d\n", local.wYear, local.wMonth, local.wDay, local.wHour, local.wMinute, local.wSecond);
    return utc;
}

SYSTEMTIME ConvertUTC2LocalTime(UINT year, UINT month, UINT day, UINT hour, UINT minute, UINT second)
{
    SYSTEMTIME local, utc;
    ZeroMemory(&utc, sizeof(utc));
    utc.wYear   = year;
    utc.wMonth  = month;
    utc.wDay    = day;
    utc.wHour   = hour;
    utc.wMinute = minute;
    utc.wSecond = second;
    SystemTimeToTzSpecificLocalTime( NULL, &utc, &local );
    printf("UTC Time  =%d/%d/%d %d:%d:%d\n", utc.wYear, utc.wMonth, utc.wDay, utc.wHour, utc.wMinute, utc.wSecond);
    printf("Local Time=%d/%d/%d %d:%d:%d\n", local.wYear, local.wMonth, local.wDay, local.wHour, local.wMinute, local.wSecond);
    return local;
}

Reference：

• TzSpecificLocalTimeToSystemTime Function
• SystemTimeToTzSpecificLocalTime Function

[Win32 API] String Conversion

在Windows底下做字串轉換其實還滿簡單的，在MFC的Library裡，提供了一些簡單的Marco可以用，就可以針對wstring, string, CComBSTR, BSTR之間做轉換了。需 Include AtlBase.h, AtlConv.h

以下是 ATL7.0 版 Marco、Class的命名規則

CSourceType2[C]DestinationType[EX]

以下是 ATL3.0 舊版 Marco的命名規則

SourceType2[C]DestinationType[EX]