[fpc-pascal] Program without window but messages

Sven Barth pascaldragon at googlemail.com
Wed Apr 25 10:01:27 CEST 2012

Am 24.04.2012 18:25, schrieb J├╝rgen Hestermann:
> I wanted to write a program that has no window but may show messages to
> the user.
> I have lots of such programs written with Virtual Pascal but I am
> struggling
> to do the same with Free Pascal/Lazarus.
> A simple test program would look like this:
> --------------------------------
> program Test;
> {$mode objfpc}{$H+}
> uses Interfaces,Forms,Windows,SysUtils,Dialogs;
> {$R *.res}
> begin
> ShowMessage('TEST');
> end.
> --------------------------------
> When I create a new project and select to create an "Application",
> copy the above into the main program (ignoring Unit1.pas) and run
> the program I get an exception "Fensterklasse nicht gefunden" (in
> german, although I setup Lazarus in english!) and I am put into
> Win32WSControls.

This specific exception could be the result of a 
SysErrorMessage(GetLastOSError) which on Windows uses the routines of 
Windows to translate the error and thus will be in the language your OS 
is setup for. (Note: this is a guess, but maybe a very valid one ;) )

> When I try the same with a new "Program" and use the same test file
> (just omitting Interfaces and Forms units, because Lazarus cannot find it.
> Why? I did find it when creating an "Application") I cannot even
> compile it because I get:
> project1.lpr(10,12) Error: Identifier not found "ShowMessage"
> The wiki ( http://wiki.freepascal.org/Dialog_Examples/de#ShowMessage )
> says that this function is definied in Dialogs which I included in my
> uses clause. Still it cannot find it. Why is ShowMessage not available?
> Creating a console program is not an option because it will create a
> console window which I don't need.
> Anybody who knows why it is like that?

As you are using LCL functions it would be better if you ask such things 
on the Lazarus list.


More information about the fpc-pascal mailing list