Get Windows Major & Minor Version

uses Registry

var
  Form1: TForm1;
  FWinVerMaj : integer;
  FWinVerMin : integer;
  FWinBuild : integer;
  FWinProdName : string;
  
//

function CheckWinVer(var WinVerMaj : integer;
                     var WinVerMin : integer;
                     var WinVerBuild : integer;
                     var WinProdName : string;
                     ShowMsg : boolean) : boolean;
var
  reg: TRegistry; // USES: Registry
  s1, s2 : string;
  MemVerMaj : integer;
  MemVerMin : integer;
  MemVerBuild : integer;
  MsgType : TMsgDlgType;
begin
  result := true;
  //MsgType := TMsgDlgType.mtInformation;
  MemVerMaj := WinVerMaj;
  MemVerMin := WinVerMin;
  MemVerBuild := WinVerBuild;
  reg := TRegistry.Create(KEY_READ);
  reg.RootKey := HKEY_LOCAL_MACHINE;
  if reg.OpenKey('SOFTWARE\Microsoft\Windows NT\CurrentVersion',false) then
  begin
    // since WIN 10:
    try
      WinVerMaj := reg.ReadInteger('CurrentMajorVersionNumber'); // dword:0000000a
      WinVerMin := reg.ReadInteger('CurrentMinorVersionNumber'); // dword:00000000
    except
      WinVerMaj := -1;
      WinVerMin := 0;
    end;
    if (WinVerMaj < 0) then
    begin
      s1 := reg.ReadString('CurrentVersion');
      s2 := Copy(s1, 1, Pos('.', s1) - 1);
      WinVerMaj := strtoint(s2);
      s2 := Copy(s1, Pos('.', s1) + 1, length(s1));
      WinVerMin := strtoint(s2);
    end;
    s1 := reg.ReadString('CurrentBuildNumber');
    WinVerBuild := strtoint(s1);
    WinProdName := reg.ReadString('ProductName');
    s1 := 'OS-Version: ' + WinProdName + #10#13 +
          inttostr(WinVerMaj) + '.' + inttostr(WinVerMin) + ' - Build ' + inttostr(WinVerBuild);
    s2 := '';
    // check necessaryVersion
    if NOT (WinVerMaj >= MemVerMaj) then
    begin
      s2 := #10#13 + '-> Major-Version lower as expected ! (' + inttostr(MemVerMaj) + ')';
      result := false;
    end;
    // if NOT (WinVerMin >= MemVerMin) then --- nicht ganz richtig ...
    if (NOT (WinVerMaj > MemVerMaj)) AND (NOT (WinVerMin >= MemVerMin)) then
    begin
      s2 := s2 + #10#13 + ' Minor-Version lower as expected ! (' + inttostr(MemVerMin) + ')';
      result := false;
    end;
    if NOT (WinVerBuild >= MemVerBuild) then
    begin
      s2 := s2 + #10#13 + ' Build-Nr. lower as expected ! (' + inttostr(MemVerBuild) + ')';
      result := false;
    end;
    if NOT result then
      //MsgType := TMsgDlgType.mtWarning;
  end
  else
  begin
    result := false;
    //MsgType := TMsgDlgType.mtError;
    WinVerMaj := -1;
    WinVerMin := -1;
    WinVerBuild := -1;
    WinProdName := 'Unknown Version';
    s1 := 'WARNING: Determine OS-Version failed !';
    s2 := '';
  end;
  reg.CloseKey();
  reg.Free;
  //if ShowMsg then
  begin
    //MessageDlg(s1 + s2, MsgType, [mbOK], 0);
  end;
end;

Beispiel :

procedure TForm1.Button1Click(Sender: TObject);
begin
  CheckWinVer(FWinVerMaj, FWinVerMin, FWinBuild, FWinProdName, true);
  Label1.Caption := FWinProdName;
  Label2.Caption := IntToStr(FWinBuild);
  Label3.Caption := IntToStr(FWinVerMin);
  Label4.Caption := IntToStr(FWinVerMaj);
end;