Error: Internal error: Failed to read data from memory

[BubikolRamios]

Last line breakpoint, move mouse on imageDragHolderEllipseCenter ... Error: Internal error: Failed to read data from memory

Code: Pascal  [Select][+][-]

1. procedure TForm1.PaintBox1MouseUp(Sender: TObject; Button: TMouseButton;
2.   Shift: TShiftState; X, Y: Integer);
3. var
4.   diameter:integer = 4;
5.   P1, P2, P3, P4: TPoint;
6.   //Points: Array of TPoint;
7.   Points_Polybezier: Array[0..3] of TPoint; // 4 pare koordinat x in y
8.   a,b:TPoint;
9.   i: integer;
10.   imageDragHolder,imageDragHolderEllipseCenter,imageDragHolderEllipseDiameter1,imageDragHolderEllipseDiameter2: Timage;
11.   AppName,AppPath: String;
12.   toCanvasCenterX,toCanvasCenterY: integer;
13. begin
14.   toCanvasCenterX := round(PaintBox1.width/2);
15.   toCanvasCenterY := round(PaintBox1.Height/2);
16.  
17.   if dragHolderEllipseAddCheckBox.Checked then
18.   begin
19.     if imageDragHolderEllipseCenter.parent = nil then  
20.  

strange, because if I extract only the code that "if imageDragHolderEllipseCenter.parent = nil" works, and put it under button click, works as expected,
i.e. parent is nil.

Code: Pascal  [Select][+][-]

1. procedure TForm1.Button15Click(Sender: TObject);
2. var
3.  
4.   imageDragHolder,imageDragHolderEllipseCenter,imageDragHolderEllipseDiameter1,imageDragHolderEllipseDiameter2: Timage;
5.  
6. begin
7.  
8.  
9.   if dragHolderEllipseAddCheckBox.Checked then
10.   begin
11.     if imageDragHolderEllipseCenter.parent = nil then
12.     begin
13.       imageDragHolder:=Timage.Create(nil);
14.       imageDragHolder.name:= 'imageDragHolderEllipseCenter';
15.       imageDragHolder.parent := panel2;// gor je PaintBox1
16.  
17.  
18.       imageDragHolder.dragMode := dmAutomatic;
19.       imageDragHolder.AutoSize:= true;
20.       exit;
21.     end;
22.  

What is that I don't see ?

[Khrys]

You're accessing uninitialized local variables.  imageDragHolderEllipseCenter  has no well-defined value here, just garbage stack data. The second example just so happens to work by what effectively comes down to random chance.

[Thaddy]

Yup, you are absolutely right.
And he has real luck his roulette programming works at some random points.