will the pointer survive?

[Allen]

Hi all,

Will my pointer survive this conversion?

MyType_tag MyType;
MyType_tag* pMyPntr = &MyType;
int iUglyTempStorag e = (int)pMyPntr;
MyType_tag* pMyOtherPntr = (MyType_tag*)iU glyTempStorage;
--

Best wishes,
Allen

[Ivan Vecerina]

Re: will the pointer survive?

"Allen" <allen-terri-ng!@#att.net> wrote in message
news:ayZsb.5916 2$Ec1.3577677@b gtnsc05-news.ops.worldn et.att.net...[color=blue]
> Will my pointer survive this conversion?
>
> MyType_tag MyType;
> MyType_tag* pMyPntr = &MyType;
> int iUglyTempStorag e = (int)pMyPntr;
> MyType_tag* pMyOtherPntr = (MyType_tag*)iU glyTempStorage;[/color]

No. (except on some platforms)


hth,
Ivan
--

http://ivan.vecerina.com

[Chris Theis]

Re: will the pointer survive?


"Allen" <allen-terri-ng!@#att.net> wrote in message
news:ayZsb.5916 2$Ec1.3577677@b gtnsc05-news.ops.worldn et.att.net...[color=blue]
> Hi all,
>
> Will my pointer survive this conversion?
>
> MyType_tag MyType;
> MyType_tag* pMyPntr = &MyType;
> int iUglyTempStorag e = (int)pMyPntr;
> MyType_tag* pMyOtherPntr = (MyType_tag*)iU glyTempStorage;
> --
>
> Best wishes,
> Allen
>[/color]

Not necessarily, though your conversion will (more or less) succeed as
you're forcing the compiler to obey your wish. Generally you might get away
with this on some platforms but it's not guaranteed to work and it's
certainly not portable.

Chris

[Unforgiven]

Re: will the pointer survive?

Allen wrote:[color=blue]
> Hi all,
>
> Will my pointer survive this conversion?
>
> MyType_tag MyType;
> MyType_tag* pMyPntr = &MyType;
> int iUglyTempStorag e = (int)pMyPntr;
> MyType_tag* pMyOtherPntr = (MyType_tag*)iU glyTempStorage;[/color]

Only if you're using a platform where an int is the same size as a pointer.

--
Unforgiven

"You can't rightfully be a scientist if you mind people thinking
you're a fool."

[EventHelix.com]

Re: will the pointer survive?

> int iUglyTempStorag e = (int)pMyPntr;

The above line is the source of trouble. Here it assumes that the
pointer and the integer are of the same size. This may not be
true on several platforms.

Sandeep
--

http://www.EventHelix.com/EventStudio

EventStudio 2.0 - Generate Sequence Diagrams and Use Case Diagrams in PDF

[Nils Petter Vaskinn]

Re: will the pointer survive?

On Fri, 14 Nov 2003 05:15:50 +0000, Allen wrote:
[color=blue]
> Will my pointer survive this conversion?
>
> MyType_tag MyType;
> MyType_tag* pMyPntr = &MyType;
> int iUglyTempStorag e = (int)pMyPntr;
> MyType_tag* pMyOtherPntr = (MyType_tag*)iU glyTempStorage;[/color]

Will this work?


MyType_tag MyType;
MyType_tag* pMyPntr = &MyType;
char *ugly[sizof(MyType_ta g*)];
memcpy(ugly,&pM yPtr,sizeof(MyT ype_tag*));
MyType_tag* pMyOtherPntr;
memcpy(&pMyOthe rPntr,ugly,size of(MyType_tag*) );


That made me feel really bad :( I think I have to go take a shower and
wash my mouth out with soap ;)

--
NPV

"the large print giveth, and the small print taketh away"
Tom Waits - Step right up

[Allen]

Re: will the pointer survive?

"EventHelix.com " <eventhelix@hot mail.com> wrote in message
news:566e2bfb.0 311140428.7c5fe 20e@posting.goo gle.com...[color=blue][color=green]
> > int iUglyTempStorag e = (int)pMyPntr;[/color]
>
> The above line is the source of trouble. Here it assumes that the
> pointer and the integer are of the same size. This may not be
> true on several platforms.[/color]

But this should only be a compile-time issue, right? Once it's
compiled, the binary image should no longer be dependant on the sizes of
types on various platforms should it?

[Jack Klein]

Re: will the pointer survive?

On Fri, 14 Nov 2003 21:22:06 GMT, "Allen" <allen-terri-ng!@#att.net>
wrote in comp.lang.c++:
[color=blue]
> "EventHelix.com " <eventhelix@hot mail.com> wrote in message
> news:566e2bfb.0 311140428.7c5fe 20e@posting.goo gle.com...[color=green][color=darkred]
> > > int iUglyTempStorag e = (int)pMyPntr;[/color]
> >
> > The above line is the source of trouble. Here it assumes that the
> > pointer and the integer are of the same size. This may not be
> > true on several platforms.[/color]
>
> But this should only be a compile-time issue, right? Once it's
> compiled, the binary image should no longer be dependant on the sizes of
> types on various platforms should it?[/color]

Once it's compiled, the binary image will not be compatible with
various platforms that have different sizes for types.

--
Jack Klein
Home: http://JK-Technology.Com
FAQs for
comp.lang.c http://www.eskimo.com/~scs/C-faq/top.html
comp.lang.c++ http://www.parashift.com/c++-faq-lite/
alt.comp.lang.l earn.c-c++ ftp://snurse-l.org/pub/acllc-c++/faq

[Rolf Magnus]

Re: will the pointer survive?

Allen wrote:
[color=blue]
> "EventHelix.com " <eventhelix@hot mail.com> wrote in message
> news:566e2bfb.0 311140428.7c5fe 20e@posting.goo gle.com...[color=green][color=darkred]
>> > int iUglyTempStorag e = (int)pMyPntr;[/color]
>>
>> The above line is the source of trouble. Here it assumes that the
>> pointer and the integer are of the same size. This may not be
>> true on several platforms.[/color]
>
> But this should only be a compile-time issue, right? Once it's
> compiled, the binary image should no longer be dependant on the sizes
> of types on various platforms should it?[/color]

Well, I don't know what you mean, but if you compile it for a platform
on which a pointer is bigger than an int (like e.g. virtually all 64bit
platforms), it will never work, even if there are other platforms on
which int and pointers are the same size.