OS version detection for 32 and 64 bit OS.

I needed to check the OS and on different OS the different path needed to be followed and so the host operating system version was needed for an application I was developing.

Background

First I would like to make a table where we know what are the platformId, MajorVersion, MinorVersion of each of the Window'sOS. Here are the PlatformId, Major and Minor Version Numbers of the 32-bit Windows operating systems Table

Code:

+----------+------------+-------+-------+
| Version  | PlatformId | Major | Minor |
+----------+------------+-------+-------+
| Win95    |      1     |   4   |   0   |
| Win98    |      1     |   4   |  10   |
| WinME    |      1     |   4   |  90   |
| WinNT351 |      2     |   3   |  51   |
| WinNT4   |      2     |   4   |   0   |
| Win2000  |      2     |   5   |   0   |
| WinXP    |      2     |   5   |   1   |
| Win2003  |      2     |   5   |   2   |
| WinCE    |      3     |   ?   |   ?   |
| WinLH    |      2     |   6   |   0   |
+----------+------------+-------+-------+

Coding

Now lets begin the OS detection code and for that we need some constants. Lets define the constants first

Code:

typedef enum OSVersion
{
    WIN95 = 1,
    WIN98 = 2,
    WINME = 3,
    WINNT351 = 4,
    WINNT4 = 5,
    WIN2000 = 6,
    WINXP = 7,
    WIN2003 = 8,
    WINCE = 9,
    WINLH = 10,
    WIN64BIT = 11
} OS_VERSION;

Now lets write a general routine to detect the OS. Here is the function to detect the OS.

Code:

OS_VERSION GetHostOS()
{
	BOOL bIs64BitOS = FALSE;
	BOOL bIsWin95 = FALSE;
	BOOL bIsWin98 = FALSE;
	BOOL bIsWinME = FALSE;
	BOOL bIsWinNT351 = FALSE;
	BOOL bIsWinNT4 = FALSE;
	BOOL bIsWin2000 = FALSE;
	BOOL bIsWinXP = FALSE;
	BOOL bIsWin2003 = FALSE;
	BOOL bIsWinLH = FALSE;
	
	// We check if the OS is 64 Bit
	typedef BOOL (WINAPI *LPFN_ISWOW64PROCESS) (HANDLE, PBOOL);

	LPFN_ISWOW64PROCESS 
	fnIsWow64Process = (LPFN_ISWOW64PROCESS)GetProcAddress(
	GetModuleHandle("kernel32"),"IsWow64Process");
 
	if (NULL != fnIsWow64Process)
	{
		if (!fnIsWow64Process(GetCurrentProcess(),&bIs64BitOS))
		{
			// handle error
		}
	}

	OSVERSIONINFO osvi;
	osvi.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
	::GetVersionEx( &osvi );
	
	bIsWin95 =
	   (osvi.dwPlatformId == VER_PLATFORM_WIN32_WINDOWS) &&
	   (osvi.dwMajorVersion == 4) &&
	   (osvi.dwMinorVersion == 0);

	bIsWin98 =
 	   (osvi.dwPlatformId == VER_PLATFORM_WIN32_WINDOWS) &&
	   (osvi.dwMajorVersion == 4) &&
	   (osvi.dwMinorVersion == 10);

	bIsWinME = 
	   (osvi.dwPlatformId == VER_PLATFORM_WIN32_WINDOWS) &&
	   (osvi.dwMajorVersion == 4) &&
	   (osvi.dwMinorVersion == 90); 

	bIsWinNT351 = 
	   (osvi.dwPlatformId == VER_PLATFORM_WIN32_NT) &&
	   (osvi.dwMajorVersion == 3) &&
	   (osvi.dwMinorVersion == 51);

	bIsWinNT4 = 
	   (osvi.dwPlatformId == VER_PLATFORM_WIN32_NT) &&
	   (osvi.dwMajorVersion == 4) &&
	   (osvi.dwMinorVersion == 0);

	bIsWin2000 = 
	   (osvi.dwPlatformId == VER_PLATFORM_WIN32_NT) &&
	   (osvi.dwMajorVersion == 5) &&
	   (osvi.dwMinorVersion == 0);

	bIsWinXP = 
	   (osvi.dwPlatformId == VER_PLATFORM_WIN32_NT) &&
	   (osvi.dwMajorVersion == 5) &&
	   (osvi.dwMinorVersion == 1);

	bIsWin2003 = 
	   (osvi.dwPlatformId == VER_PLATFORM_WIN32_NT) &&
	   (osvi.dwMajorVersion == 5) &&
	   (osvi.dwMinorVersion == 2);

	bIsWinLH = 
	    (osvi.dwPlatformId == VER_PLATFORM_WIN32_NT) &&
	    (osvi.dwMajorVersion == 6);

	if( bIs64BitOS ) return WIN64BIT;
	if( bIsWin95 ) return WIN95;
	if( bIsWin98 ) return WIN98;
	if( bIsWinME ) return WINME;
	if( bIsWinNT351 ) return WINNT351;
	if( bIsWinNT4 ) return WINNT4;
	if( bIsWin2000 ) return WIN2000;
	if( bIsWinXP ) return WINXP;
	if( bIsWin2003 ) return WIN2003;
	if( bIsWinLH ) return WINLH;

	return WINXP;
}

I have skipped the WINCE but that can be easily added with the help of the above table.