What is wrong with this small code ?
lazarus / 9-Editor

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GoDxNero · 2009-10-19 20:19

Well I want so that once I type this word 'asd' i will receive a var

procedure ........onkeypress.....
begin
   if key = 'a' then
     if key = 's' then
       if key = 'd' then
       a := 5;
end;

how to write it the correct way ?

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alter · 2009-10-19 21:47

for example:

create global variable key_state: integer;
set it to 0 on application startup

and then:
Code: [Select]procedure ........onkeypress.....
begin
   case key of
     'a': if key_state = 0 then key_state:=1;
     's': if key_state = 1 then key_state:=2;
     'd': if key_state = 2 then begin
         key_state:=0;
         a:=5;
       end;
   end;
end;

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Martin_fr · 2009-10-19 21:54

..OnKeyPress is called once for each keypress. So if someone types asd
then there are 3 calls to the event.

your code assumes that key is a s and d at the *same* time => which
will never be true.

you need to keep a "state" (a common thing in all software
development).

For this you need to store the value of the state in a place where it
will persist between the individual calls to the OnKeyPress events.

Best to do is to create a Member (variable) in the object. Assuming
that this is  Form1.Edit1KeyPress => then TForm1 is the object that
should have your state variable.

TForm1 = class
  .... //lots of automatically created stuff
 private
   asdState: Integer;
....

procedure ........onkeypress.....
begin
   if key = 'a' then asdState := 1
   else
   if key = 's' and asdState = 1 then asdState := 2
   else
   if key = 'd' and asdState = 0 then begin
       a:=5
       asdState := 0;
   end
   else
       asdState := 0;
end;

Now if asdState is 1, we know the previous key was an "a".
It will be increased by one, if the next correct char is enterred.
Any other char will reset it, so the whole sequence must be entered
again.

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Martin_fr · 2009-10-19 21:58

@alter

always prefer a variable on the object, over a global. global
variables are harder to maintain on the long run.

Your code does not reset the  key_state  if any other char is pressed.
so it will also work for axysxyd

The case is preferable over the multi-if that I used => +1

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alter · 2009-10-20 11:35

Sorry, I was writing it late night:-) Ofc case needs also else part
and by global i meant out of procedure ofc

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GoDxNero · 2009-10-20 14:49

It actually not works

private
    { private declarations }
    cheatState: Integer;

procedure TForm1.FormKeyPress(Sender: TObject; var Key: char);
begin
  if key = 'h' then cheatState := 1
  else
  if (key = 'a') and (cheatState = 1) then cheatState := 2
  else
  if (key = 'i') and (cheatState = 2) then
  begin
    correct:=10;
    Label1.Caption := 'Level 10 of 10';
    Form1.Color := clBlack;
    resets;
    cheatState := 0;
  end
  else cheatState := 0;
end;

Edit : Sorry It works ! I forget 'keyPreview' = true