Mail Archives: djgpp/1999/08/01/20:19:36
From: | "Ole Laursen" <ole_laursen AT hardworking DOT dk>
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Newsgroups: | comp.os.msdos.djgpp
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References: | <37a49d74 AT news DOT ismi DOT net>
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Subject: | Re: BITMAP pointers w/ Allegro.
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Lines: | 39
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Message-ID: | <0I2p3.31$l4.1288@news030.image.dk>
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Date: | Sun, 1 Aug 1999 23:07:34 +0200
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To: | djgpp AT delorie DOT com
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DJ-Gateway: | from newsgroup comp.os.msdos.djgpp
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Reply-To: | djgpp AT delorie DOT com
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> main(void)
> {
> BITMAP *bmp;
> function(bmp);
> }
>
> function(BITMAP *bmp)
> {
> bmp = create_bitmap(320, 240);
> }
>
> How do I pass the bitmap by reference so I can edit its value in
> sub-functions?
This will do, I think (warning: I haven't tested it, might have made a
mistake):
main(void)
{
BITMAP *bmp;
function(&bmp); // passing address
}
function(BITMAP **bmp) // getting pointer to pointer to BITMAP
{
*bmp = create_bitmap(320, 240); // first dereference, then assign
}
So you use a pointer to a BITMAP-pointer to refer to the address of the
BITMAP-pointer variable, thereby being able to change the variable. There
are other possibilities, too, e.g. if you had been using C++ you could have
used a reference with a '&'.
--
Ole Laursen - http://sunsite.auc.dk/olau/
Row, row, row your boat, gently down the streeaam (gee!)
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