How to stop console window from closing immediately | GNAT - GPS

Question

I have Ada program that runs and compile perfectly using GNAT - GPS. When I run its exe file and provide user input then instead of saying "Press any key to continue", the exe closes immediately.

I have searched for it online alot but i only found info related to c/c++/visual studio console window using system('pause'); OR Console.Readline().

Is there any way around for this in Ada lanaguage?

Answer 1

Apart from using Get_Line or Get, you can also use Get_Immediate from the Ada.Text_IO package. The difference is that Get_Line and Get will continue to read user input until <Enter> has been hit, while Get_Immediate will block only until a single key has been pressed when standard input is connected to an interactive device (e.g. a keyboard).

Here's an example:

with Ada.Text_IO; use Ada.Text_IO;

procedure Main is
begin

   --  Do some interesting stuff here...   

   declare
      User_Response : Character;
   begin
      Put_Line ("Press any key to continue...");
      Get_Immediate (User_Response);
   end;

end Main;

NOTES

• You should run the program in an interactive terminal (Bash, PowerShell, etc.) to actually see the effect of Get_Immediate. When you run the program from within GPS, then you still have to press enter to actually exit the program.

• This might be too much detail, but I think that Get still waits for <Enter> to be pressed because it uses fgetc from the C standard library (libc) under the hood (see here and here). The function fgetc reads from a C stream. C streams are initially line-buffered for interactive devices (source).