Message-ID: <3688953A.6E209BE8@ulster.net>
Date: Tue, 29 Dec 1998 03:39:23 -0500
From: Keith <sunfish18 AT yahoo DOT com>
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Newsgroups: comp.os.msdos.djgpp
To: djgpp AT delorie DOT com
Subject: Re: ? strange problem
References: <F02EDE79D030D11192BA006008136ED11A61CE AT pamela DOT x3m DOT se>
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Reply-To: djgpp AT delorie DOT com

Ztream,

you're right about this, but i did get the same bug that the origional person
was talking about... an integer w/in a class went bad somehow when i was passing
it out of a switch statement... i know this is exactly where it happend because
i had it "cout" the values at every point in the prog... but the program worked
fine when i assigned the origional class to a second class of the same type w/in
the switch statement (just before it went bad) and then used that second class
outside the switch statement... also, this program compiled fine in the borland
compiler w/o this modification...

thanks,
steve

Ztream wrote:

> > -----Original Message-----
> > From: twidler444 AT aol DOT com [SMTP:twidler444 AT aol DOT com]
> > Sent: Monday, December 21, 1998 7:19 AM
> > To:   djgpp AT delorie DOT com
> > Subject:      Re: ? strange problem
> >
>         >Hello
>         >   I couldn't find the earlier posting, But I think I know what you
> are talking
>         >about, and how to fix it.
>
>         >does your code look something like this?
>
>         >typedef struct TEST
>         >{
>         >int x,y;
>         >}TEST;
>         >
>         >TEST it;
>         >
>         >int main()
>         >{
>         >TEST temp;
>         >
>         >temp=it;
>         >temp.x=10;
>         >temp.y=50;
>         >
>         >// then here is were you find out that it.x isnt 10
>         >}
>
> The reason it.x isn't 10 is because it is simply never set to 10. temp is
> not a pointer. temp=it copies all member fields from "it" to temp, but temp
> is still a completely independent variable; what you do to temp does not and
> should not affect "it" in any way.
>
> I guess that what you mean to do is something like the following:
>
> int main()
> {
> TEST *temp;
>
> temp=&it;
> temp->x=10;
> temp->y=50;
> }
>
> This correctly alters "it" as you are altering temp->x.
>
>         >I found that in DJGPP(and other free compilers) that you can only
> read from
>         >temp.x and not write.
>
> I feel rather confident that the above should not work under *any* compiler
> (*that* would be a bug). Please correct me if I'm wrong, but I tested both
> your original code and my altered code, and they both confirmed what I'm
> saying.
>
> Or, perhaps you just made an error in the comment on the last line, actually
> meaning temp.x ;) This does, however, work as expected, and the rest of the
> mail seems to confirm that you do mean what you typed.
>
> Hope this is of help :)
>
> / Z
>
> ---------------------------------------------------------------------------
> Ztream / 1x4x9 - "The white dwarf"
> ztream AT x3m DOT se \ www.highrad.x3m.se/Ztream
> Free your mind.