Is there a way I can detect that a user has pushed the red X in the upper right corner to close the console window in a free pascal console application so I can save some files before the program terminates?

James

At least on Unix systems I'd assume the answer was to write a signal handler: https://www.freepascal.org/docs-html/rtl/baseunix/fpsigaction.html

Kevin

Kevin Lyda wrote

At least on Unix systems I'd assume the answer was to write a signal handler: https://www.freepascal.org/docs-html/rtl/baseunix/fpsigaction.html

IME, that should always be done... especially in the *nix world... you never know where termination may come from and providing a clean exit is much preferable to an uncontrolled exit...

Is there a way I can detect that a user has pushed the red X in the upper right corner to close the console window in a free pascal console application so I can save some files before the program terminates?

You can do that with SetConsoleCtrlHandler() and catching CTRL_CLOSE_EVENT in the handler.

Henry

Could I please get an example of this? I see lots of examples of how to do it in C but when I try to translate to pascal I always struggle a quite a bit.

James

James Richters wrote

Could I please get an example of this? I see lots of examples of how to do it in C but when I try to translate to pascal I always struggle a quite a bit.

Have a look at the fpc source in packages/fv/src/w32msg.inc and search for SetConsoleCtrlHandler and then HandleConsoleCtrl. There's nothing to it, really.

Henry

Thanks! That was quite helpful! I have a test program kind of working.

I notice I only get 5 seconds to do what I am going to before it closes, and I also notice that my program can no longer respond to keystrokes after I hit the red X. How do other programs get around this? For example if I open word for windows and type something and hit the X it asks if I want to save it and will wait indefinitely for a response. Is this a limitation because I am running console application, Is there a way I can do this with my console application as well?

Here is my test program:

uses crt,windows;
var x,y: longint;
    Closetheprogram:Boolean;
Function Console_Handler(dwCtrlType: Dword) : BOOL; stdcall;
Begin
  Console_Handler:=false;
  Case dwCtrlType of
    CTRL_CLOSE_EVENT,
    CTRL_LOGOFF_EVENT,
    CTRL_SHUTDOWN_EVENT :
      begin
         Console_Handler:=True;
         CloseTheProgram:=True;
          Writeln('start');
          For X:= 1 to 2000000 do  //this keeps the Console_Handler busy so my program continues to execute;
              Begin
                 sleep(1);
                 inc(y);
              end;
          Writeln('stop');
        Console_Handler:=True;
        CloseTheProgram:=True;
      end;
  end;
end;
Begin
CloseTheProgram:=False;
if SetConsoleCtrlHandler(@Console_handler, TRUE) then
   Writeln('Console CTRL Handler Installed')
else
   Writeln('Console CTRL Handler Not Installed');
Repeat
Write('.');
Sleep(100);
Until CloseTheProgram or keypressed;
If Keypressed then
Repeat
readkey;
Until not(Keypressed);
Repeat
Write(',');
Sleep(100);
Until keypressed;
Writeln(ClosetheProgram);
end.

James Richters schrieb am So., 19. Mai
2019, 19:10:

Correct, that is a limitation of the console no matter the operating system.

Regards,
Sven

Thanks for clarifying, I have everything working well now in my real program, I didn’t need to do anything other than save and close some files, so I have plenty of time to get everything done.

James