procedure TForm1.Button1Click(Sender: TObject);
var
  sBuffer:   PChar;
  sSize:   Cardinal;
begin
  sSize   :=   255;
  GetMem(sBuffer,   sSize   +   1);
  try
    if   GetComputerName(sBuffer,   sSize)   then
      label1.caption   :=   sBuffer;
  finally
  FreeMem(sBuffer);
end;
end;
//delphi/5070