How to check whether a program is available on a PC

Problem/Question/Abstract:

How do you find out whether a program is available ? For example, how can you programmatically tell whether MS Word 2000 is installed rather than Lotus WordPro? The OS can be Win95, 98, ME, 2000, NT4. I did not find any Win API function allowing to find out if a specific application exists on the machine. The nearest I found is the FindExecutable function but you need to pass it a document file name. Should I read the registry, to enumerate the currently installed applications?

Answer:

For the MS Word case, you might want to start Word in automation mode to see if its present. The following routine does that:

function IsWordPresent(var IsActive: Boolean): Boolean;
var
  MSWord: Variant;
begin
  Result := False;
  IsActive := False;
  try
    MSWord := GetActiveOleObject('Word.Application');
    Result := not VarIsEmpty(MSWord);
    IsActive := not VarIsEmpty(MSWord)
  except
    MSWord := Unassigned
  end;
  if VarIsEmpty(MSWord) then
  begin
    try
      MSWord := CreateOleObject('Word.Application');
      Result := not VarIsEmpty(MSWord);
      if Result then
        MSWord.Quit
    except
    end;
  end;
end;