Check the registry

Windows NT
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\CurrentVersion

Yes, I know VB code, but this was the first code snippet I could find. If you understand this, it shouldn''t be very hard to port to C++. Hope this helps.


Public Const HKEY_LOCAL_MACHINE = &H80000002

Public Const REG_SZ = 1 ''Unicode nul terminated string
Public Const REG_BINARY = 3 ''Free form binary
Public Const REG_DWORD = 4 ''32-bit number
Public Const ERROR_SUCCESS = 0&
Public Const ERROR_FILE_NOT_FOUND = 2

Private Declare Function RegCloseKey Lib "advapi32.dll" (ByVal hKey As Long) As Long
Private Declare Function RegOpenKey Lib "advapi32.dll" Alias "RegOpenKeyA" (ByVal hKey As Long, ByVal lpSubKey As String, phkResult As Long) As Long
Private Declare Function RegQueryValueEx Lib "advapi32.dll" Alias "RegQueryValueExA" (ByVal hKey As Long, ByVal lpValueName As String, ByVal lpReserved As Long, lpType As Long, lpData As Any, lpcbData As Long) As Long


Public Function GetRegKeyString(hKey As Long, _
strPath As String, strValue As String, Optional _
Default As String) As String
Dim hCurKey As Long
Dim lResult As Long
Dim lValueType As Long
Dim strBuffer As String
Dim lDataBufferSize As Long
Dim intZeroPos As Integer
Dim lRegResult As Long

''Set up default value
If Not IsEmpty(Default) Then
GetRegKeyString = Default
Else
GetRegKeyString = ""
End If

lRegResult = RegOpenKey(hKey, strPath, hCurKey)

If (lRegResult = ERROR_FILE_NOT_FOUND) Then
GetRegKeyString = vbNullString
lRegResult = RegCloseKey(hCurKey)
Exit Function
End If

lRegResult = RegQueryValueEx(hCurKey, strValue, 0&, lValueType, ByVal 0&, lDataBufferSize)

If lRegResult = ERROR_SUCCESS Then
If lValueType = REG_SZ Then
strBuffer = String(lDataBufferSize, " ")
lResult = RegQueryValueEx(hCurKey, strValue, 0&, 0&, ByVal strBuffer, lDataBufferSize)
intZeroPos = InStr(strBuffer, Chr$(0))

If intZeroPos > 0 Then
GetRegKeyString = Left$(strBuffer, intZeroPos - 1)
Else
GetRegKeyString = strBuffer
End If
End If
ElseIf (lRegResult = ERROR_FILE_NOT_FOUND) Then
GetRegKeyString = vbNullString
lRegResult = RegCloseKey(hCurKey)
Exit Function
Else
VBA.Err.Raise ERR_FATAL
End If

lRegResult = RegCloseKey(hCurKey)
End Function

Here''s som more or less pseudo-code that should work.
Note that you''ll have to define the os-name constants yourself before trying it.

int get_os(){	OSVERSIONINFO osinf; 	osinf.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);	GetVersionEx(&osinf); 	switch(osinf.dwPlatformId)	{	case VER_PLATFORM_WIN32_NT: 		if (osinf.dwMajorVersion == 3)			return OS_WINDOWS_NT3;		if (osinf.dwMajorVersion == 4)			return OS_WINDOWS_NT4;		if (osinf.dwMajorVersion == 5 && osinf.dwMinorVersion == 0)			return OS_WINDOWS_2000; 		if (osinf.dwMajorVersion >= 5 || (osinf.dwMajorVersion == 5 && osinf.dwMinorVersion > 0))			return OS_WINDOWS_XP;	//Windows XP, and it''s followers! (if any) 		break;	case VER_PLATFORM_WIN32_WINDOWS: 		if (osinf.dwMinorVersion == 0)			return OS_WINDOWS_95; 		if (osinf.dwMinorVersion == 10)			return OS_WINDOWS_98;		if (osinf.dwMinorVersion == 90) 			return OS_WINDOWS_ME;		break;	case VER_PLATFORM_WIN32s: 		return OS_WINDOWS_32S;	} 	return (-1);	//Unknown}