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Re: [PATCH] Clean code to be 64bit clean

From: Jani Averbach <jaa_at_jaa.iki.fi>
Date: 2003-11-30 22:16:36 CET

On 2003-11-30 21:58+0100, Tobias Ringstrom wrote:
> Jani Averbach wrote:
> >
> >This message is a little bit bogus, only problem seems to be that
> >there are tree compiler warnings of void * to integer conversion or
> >vice versa (when orginal data has been integer any way from the start).
> I'm not sure I understand what the problem is here. Do you really get
> a compiler warning if you cast a void* to an int?

Yep [1], this is a 64bit [2] system. It seems to be that in 32bit gcc
systems sizeof(int) == sizeof(long). Moreover, in general long is only
type that is supposed (in practice) to hold void *, but this is not
required by standard, so you should not count on it everywhere.

So in theory casting void * -> int is not a safe operation, but when
we are using void * just carrying data, in fact, it is.

BR, Jani

warning: cast from pointer to integer of different size

#include <stdio.h>

    printf("int %d\n", sizeof(int));
    printf("long %d\n", sizeof(long));
    printf("void * %d\n", sizeof(void *));
    return 0;


int 4
long 8
void * 8

Jani Averbach
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Received on Sun Nov 30 22:17:07 2003

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