Re: Get_Immediate has raised CONSTRAINT_ERROR : s-wchcnv.adb:207 explicit raise

["Björn Lundin" <b.f.lundin@gmail.com>]

On 2015-02-18 18:29, darek wrote:
> Dear All,
>   reading from a keyboard  keys such as arrow keys, PgUp, PgDn, etc. seems to be a small challenge in Ada.  For this purpose one of the  Get_Immediate procedures from the Ada.Text_IO shall be used. For the keyboard we can use either 
>   - procedure Get_Immediate  (Item : out Character) 
>                or
>   - procedure Get_Immediate  (Item      : out Character; Available : out Boolean)
> 

if you use SDL, I think it will do the trick. I have some code that does

      SDL.Events.PollEventVP (PollEvent_Result, Event);
      exit when PollEvent_Result = 0;
      case Event.The_Type is
         when SDL.Events.KEYDOWN =>
           declare
             -- player 0 -> w,a,s,z
             -- player 1 -> up,left,rigt,down
             Name_Of_Key : String :=
C.Strings.Value(SDL.Keyboard.GetKeyName(Event.key.keysym.sym));
           begin
             Log("Game.Handle_Events"," Key down: '" & Name_Of_Key & "'");
             if    Name_Of_Key = "up" then
               Game.Player(Player_Idx).Game_Obj_Ptr.Heading := Up;
             elsif Name_Of_Key = "right" then
               Game.Player(Player_Idx).Game_Obj_Ptr.Heading := Right;
             elsif Name_Of_Key = "down" then
               Game.Player(Player_Idx).Game_Obj_Ptr.Heading := Down;
             elsif Name_Of_Key = "left" then
....




--
Björn