Note: Gabr is asking about an approach that can bypass the limitations of GetVersionEx. JCL code uses GetVersionEx, and is thus subject to compatibility layer. This information is for people who don't need to bypass the compatibility layer, only.
Using the Jedi JCL, you can add unit JclSysInfo, and call function GetWindowsVersion. It returns an enumerated type TWindowsVersion.
Currently JCL contains all shipped windows versions, and gets changed each time Microsoft ships a new version of Windows in a box:
TWindowsVersion =
(wvUnknown, wvWin95, wvWin95OSR2, wvWin98, wvWin98SE, wvWinME,
wvWinNT31, wvWinNT35, wvWinNT351, wvWinNT4, wvWin2000, wvWinXP,
wvWin2003, wvWinXP64, wvWin2003R2, wvWinVista, wvWinServer2008,
wvWin7, wvWinServer2008R2);
If you want to know if you're running 64-bit windows 7 instead of 32-bit, then call JclSysInfo.IsWindows64.
Note that JCL allso handles Editions, like Pro, Ultimate, etc. For that call GetWindowsEdition, and it returns one of these:
TWindowsEdition =
(weUnknown, weWinXPHome, weWinXPPro, weWinXPHomeN, weWinXPProN, weWinXPHomeK,
weWinXPProK, weWinXPHomeKN, weWinXPProKN, weWinXPStarter, weWinXPMediaCenter,
weWinXPTablet, weWinVistaStarter, weWinVistaHomeBasic, weWinVistaHomeBasicN,
weWinVistaHomePremium, weWinVistaBusiness, weWinVistaBusinessN,
weWinVistaEnterprise, weWinVistaUltimate, weWin7Starter, weWin7HomeBasic,
weWin7HomePremium, weWin7Professional, weWin7Enterprise, weWin7Ultimate);
For historical interest, you can check the NT-level edition too with the NtProductType function, it returns:
TNtProductType = (ptUnknown, ptWorkStation, ptServer, ptAdvancedServer,
ptPersonal, ptProfessional, ptDatacenterServer,
ptEnterprise, ptWebEdition);
Note that "N editions" are detected above. That's an EU (Europe) version of Windows, created due to EU anti-trust regulations. That's a pretty fine gradation of detection inside the JCL.
Here's a sample function that will help you detect Vista, and do something special when on Vista.
function IsSupported:Boolean;
begin
case GetWindowsVersion of
wvVista: result := false;
else
result := true;
end;
end;
Note that if you want to do "greater than" checking, then you should just use other techniques. Also note that version checking can often be a source of future breakage. I have usually chosen to warn users and continue, so that my binary code doesn't become the actual source of breakage in the future.
Recently I tried to install an app, and the installer checked my drive free space, and would not install, because I had more than 2 gigabytes of free space. The 32 bit integer signed value in the installer became negative, breaking the installer. I had to install it into a VM to get it to work. Adding "smart code" often makes your app "stupider". Be wary.
Incidentally, I found that from the command line, you can run WMIC.exe, and type path Win32_OperatingSystem (The "Select * from Win32_OperatingSystem" didn't work for me). In future perhaps JCL could be extended to use the WMI information.
