Wierd Program (or Brain) Bug...

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3 total messages Started by Nicholas Gessler Wed, 01 Aug 2001 05:35

#1225

Author: Nicholas Gessler
Date: Wed, 01 Aug 2001 05:35

47 lines
2851 bytes

This one has me stumped:
I wrote a stupid little program.  There is one form, two edit boxes, and a
MouseOver event handler.  In the handler is the code:

void __fastcall TForm1::FormMouseMove(TObject *Sender, TShiftState Shift,
      int X, int Y)
{
        EditX->Text = "       " + X;
        EditY->Text = "       " + Y;
        // Jungle Sounds
        if (X == 10) PlaySound("c:\\windows\\media\\jungle asterisk.wav",
"", SND_ASYNC);
        if (X == 20) PlaySound("c:\\windows\\media\\jungle close.wav", "",
SND_ASYNC);
        if (X == 30) PlaySound("c:\\windows\\media\\jungle critical
stop.wav", "", SND_ASYNC);
        // and so on
        // Musica Sounds
        if (Y == 10) PlaySound("c:\\windows\\media\\musica asterisk.wav",
"", SND_ASYNC);
        if (Y == 20) PlaySound("c:\\windows\\media\\musica close.wav", "",
SND_ASYNC);
        if (Y == 30) PlaySound("c:\\windows\\media\\musica critical
stop.wav", "", SND_ASYNC);
        if (Y == 40) PlaySound("c:\\windows\\media\\musica default.wav", "",
SND_ASYNC);
        // and so with Utopia and Robotz on up to 370 for all 68 Media
sounds
        // and the window is at least 400 by 400 in size.
}

So, OK, this is supposed to operate like a harp with strings in the
horizontal and vertical directions that are each attached to a sound and are
plucked when the cursor passes over them.  And the sounds work OK.

What is puzzling is what appears in the EditX and EditY boxes.  I was hoping
that the X and Y coordinates would appear.  NOPE!
As you move the cursor in the X direction, what scrolls through the Edit Box
are the names of the paths to the first 9 jungle sounds.
As you move the cursor in the Y direction, what scrolls through the Edit Box
are the names of the paths to the first 11 jungle sounds.
And I do mean "scroll" as in an LED message board.

Can anyone tell me what is going on here?  I am mystified.

Thanks,
Nick

Re: Wierd Program (or Brain) Bug...

#1226

Author: Corey Murtagh
Date: Wed, 01 Aug 2001 09:03

39 lines
2323 bytes

Nicholas Gessler <gessler@ucla.edu> wrote in message
news:3b6794e8$1_2@dnews...
> This one has me stumped:
> I wrote a stupid little program.  There is one form, two edit boxes, and a
> MouseOver event handler.  In the handler is the code:
>
> void __fastcall TForm1::FormMouseMove(TObject *Sender, TShiftState Shift,
>       int X, int Y)
> {
>         EditX->Text = "       " + X;

Here's your problem.  Adding an int to a char* will give you an index into
the array of chars.  You need to do something like:

  EditX->Text = AnsiString("       ") + Y;

Once you've got AnsiString involved in the act it properly appends the
string value of Y rather than indexing the string.

> What is puzzling is what appears in the EditX and EditY boxes.  I was
hoping
> that the X and Y coordinates would appear.  NOPE!
> As you move the cursor in the X direction, what scrolls through the Edit
Box
> are the names of the paths to the first 9 jungle sounds.

You're lucky you didn't get some random garbage, or cause an AV.  Imagine
you have a block of memory where these string constants are stored, starting
with the first one (your block of spaces) and continuing through each wav
path.  Index the space string by a large enough value and you'll find
yourself in the middle of one of the wav paths.  This is probably not far
from what's actually happening.


--
Corey Murtagh
The Electric Monk
"Quidquid latine dictum sit, altum viditur."

Re: Wierd Program (or Brain) Bug...

#1228

Author: Nicholas Gessler
Date: Thu, 02 Aug 2001 01:20

3 lines
956 bytes

Corey,
Thanks.
Nick

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