«

Lionel Valero <> writes:

> main (argc, argv)
> int argc;
> char *argv[];
> {
> int *ka;
> int nka;
>
> /* allocation dynamique entiere */
> ka = (int *) malloc(nka * sizeof(int));

I don't recommend casting the return value of malloc():

* The cast is not required in ANSI C.

* Casting its return value can mask a failure to #include
<stdlib.h>, which leads to undefined behavior.

* If you cast to the wrong type by accident, odd failures can
result.

In fact, the second problem is your problem here. Fix it.

When calling malloc(), I recommend using the sizeof operator on
the object you are allocating, not on the type. For instance,
*don't* write this:

int *x = malloc (sizeof (int) * 12; /* Don't do this! */

Instead, write it this way:

int *x = malloc (sizeof *x * 12;

There's a few reasons to do it this way:

* If you ever change the type that `x' points to, it's not
necessary to change the malloc() call as well.

This is more of a problem in a large program, but it's still
convenient in a small one.

* Taking the size of an object makes writing the statement
less error-prone. You can verify that the sizeof syntax is
correct without having to look at the declaration.

--
char a[]="\n .CJacehknorstu";int putchar(int);int main(void){unsigned long b[]
={0x67dffdff,0x9aa9aa6a,0xa77ffda9,0x7da6aa6a,0xa6 7f6aaa,0xaa9aa9f6,0x1f6},*p=
b,x,i=24;for(;p+=!*p;*p/=4)switch(x=*p&3)case 0:{return 0;for(p--;i--;i--)case
2:{i++;if(1)break;else default:continue;if(0)case 1utchar(a[i&15]);break;}}}

Hello,

I have a test program that is compiled fine on a 32 bits redhat linux using gcc :
***********************
main (argc, argv)
int argc;
char *argv[];
{
int *ka;
int nka;

/* allocation dynamique entiere */
ka = (int *) malloc(nka * sizeof(int));
if (!ka) {
printf ("<ERROR> : Out of heap space (malloc) !\n");
printf ("<ERROR> : %d int words required\n", nka);
exit (-1);
}
}
***********************

But under linux suse AMD opteron 64, i get this message from the compiler :

warning: cast to pointer from integer of different size

Any explanation ?

Regards,
Lionel.
--
-=O=------------------------------------------=O=-
Lionel Valéro
Analyste Informatique Département Génie Chimique
École Polytechnique de Montréal
C.P. 6079, succ. centre-ville
Montréal (Québec) H3C 3A7
Tel: (514) 340 - 4711 # 4805 / C552
Fax: (514) 340 - 4159
-=O=------------------------------------------=O=-

In article <nELyb.74495$>,
says...
> Hello,
>
> I have a test program that is compiled fine on a 32 bits redhat linux using gcc :
> ***********************
> main (argc, argv)
> int argc;
> char *argv[];
> {
> int *ka;
> int nka;
>
> /* allocation dynamique entiere */
> ka = (int *) malloc(nka * sizeof(int));
> if (!ka) {
> printf ("<ERROR> : Out of heap space (malloc) !\n");
> printf ("<ERROR> : %d int words required\n", nka);
> exit (-1);
> }
> }
> ***********************
>
> But under linux suse AMD opteron 64, i get this message from the compiler :
>
> warning: cast to pointer from integer of different size
>
> Any explanation ?

At a quick glance, you seem to have left out a proper header for malloc.
The compiler doesn't automagically know what "malloc" means without one.
Also, the cast is not required in C, and helps to hide this omission from
you, thereby making it harder to diagnose.

--
Randy Howard _o
2reply remove FOOBAR \<,
______________________()/ ()______________________________________________
SCO Spam-magnet:

> ka = (int *) malloc(nka * sizeof(int));

No cast.

Also, sizeof( void* ) might not equal sizeof( int* ).

--
The designer of the experimental, SMP and HyperThread friendly, AppCore
library.

http://AppCore.home.comcast.net

On Mon, 01 Dec 2003 18:21:07 GMT, Lionel Valero <>
wrote:

>Hello,
>
>I have a test program that is compiled fine on a 32 bits redhat linux using gcc :
>***********************
>main (argc, argv)
> int argc;
> char *argv[];
>{
> int *ka;
> int nka;
>
> /* allocation dynamique entiere */
> ka = (int *) malloc(nka * sizeof(int));
> if (!ka) {
> printf ("<ERROR> : Out of heap space (malloc) !\n");
> printf ("<ERROR> : %d int words required\n", nka);
> exit (-1);
> }
>}
>***********************
>
>But under linux suse AMD opteron 64, i get this message from the compiler :
>
>warning: cast to pointer from integer of different size
>
>Any explanation ?

Yes. You neglected to
#include <stdlib.h>
which defines the malloc() function's return value.

Since you did not do this, the compiler assumed that malloc() returned the
default type (int), and saw that you forced a conversion from (int) to (int *)
in your code. The compiler issued the warning based on this.

The fix is to
a) include <stdlib.h> in your code, and
b) remove the unnecessary case of malloc()'s return value.

--
Lew Pitcher
IT Consultant, Enterprise Technology Solutions
Toronto Dominion Bank Financial Group

(Opinions expressed are my own, not my employers')

I forgto the headers :
#include <stdio.h>
#include <sys/types.h>
#include <time.h>


Lionel Valero wrote:

> Hello,
>
> I have a test program that is compiled fine on a 32 bits redhat linux
> using gcc :
> ***********************
> main (argc, argv)
> int argc;
> char *argv[];
> {
> int *ka;
> int nka;
>
> /* allocation dynamique entiere */
> ka = (int *) malloc(nka * sizeof(int));
> if (!ka) {
> printf ("<ERROR> : Out of heap space (malloc) !\n");
> printf ("<ERROR> : %d int words required\n", nka);
> exit (-1);
> }
> }
> ***********************
>
> But under linux suse AMD opteron 64, i get this message from the compiler :
>
> warning: cast to pointer from integer of different size
>
> Any explanation ?
>
> Regards,
> Lionel.

--
-=O=------------------------------------------=O=-
Lionel Valéro
Analyste Informatique Département Génie Chimique
École Polytechnique de Montréal
C.P. 6079, succ. centre-ville
Montréal (Québec) H3C 3A7
Tel: (514) 340 - 4711 # 4805 / C552
Fax: (514) 340 - 4159
-=O=------------------------------------------=O=-

In article <6dMyb.74810$>,
says...
> I forgto the headers :
> #include <stdio.h>
> #include <sys/types.h>
> #include <time.h>

<sys/types.h> does not seem to be necessary for what you have below
and you will find out that it isn't portable either.

<time.h> also does not seem to be necessary, but at least is standard.

What is necessary: <stdlib.h>, as has been pointed out already in this
thread.

>
>
> Lionel Valero wrote:
>
> > Hello,
> >
> > I have a test program that is compiled fine on a 32 bits redhat linux
> > using gcc :
> > ***********************
> > main (argc, argv)
> > int argc;
> > char *argv[];
> > {
> > int *ka;
> > int nka;
> >
> > /* allocation dynamique entiere */
> > ka = (int *) malloc(nka * sizeof(int));
> > if (!ka) {
> > printf ("<ERROR> : Out of heap space (malloc) !\n");
> > printf ("<ERROR> : %d int words required\n", nka);
> > exit (-1);
> > }
> > }
> > ***********************
> >
> > But under linux suse AMD opteron 64, i get this message from the compiler :
> >
> > warning: cast to pointer from integer of different size
> >
> > Any explanation ?
> >
> > Regards,
> > Lionel.
>
>

--
Randy Howard _o
2reply remove FOOBAR \<,
______________________()/ ()______________________________________________
SCO Spam-magnet:

Lionel Valero wrote:

> I have a test program
> that is compiled fine on a 32 bits redhat linux using gcc :
> ***************

> cat malloc.c
#include <stdlib.h>
#include <stdio.h>

int main (int argc, char* argv[]) {
int nka = atoi(argv[1]);

/* allocation dynamique entiere */
int* ka = (int*)malloc(nka*sizeof(int));
if (NULL == ka) {
fprintf(stderr, "<ERROR>: Out of free storage (malloc)!\n");
fprintf(stderr, "<ERROR>: %d int words required\n", nka);
exit (EXIT_FAILURE);
}
return EXIT_SUCCESS;
}

> gcc -Wall -std=c99 -pedantic -o malloc malloc.c
> ./malloc 13
> ./malloc 999999999999
<ERROR>: Out of free storage (malloc)!
<ERROR>: 2147483647 int words required

> ***********************
>
> But under linux suse AMD opteron 64, I get this message from the compiler:
>
> warning: cast to pointer from integer of different size
>
> Any explanation?

You need to include stdlib.h which declares malloc.

Ben Pfaff wrote:

> I don't recommend casting the return value of malloc():
>
> * The cast is not required in ANSI C.

But an ANSI/ISO C++ compiler will complain.

> * Casting its return value can mask a failure to
> #include <stdlib.h>, which leads to undefined behavior.

No! It may mask the fact that malloc was not declared
but a good C compiler will warn you about that.

> * If you cast to the wrong type by accident,
> odd failures can result.

Can you show us an example?

> In fact, the second problem is your problem here. Fix it.
>
> When calling malloc(), I recommend using the sizeof operator on
> the object you are allocating, not on the type. For instance,
> *don't* write this:
>
> int *p = malloc (sizeof (int) * 12; /* Don't do this! */
>
> Instead, write it this way:
>
> int *p = malloc (sizeof *p * 12;
>
> There's a few reasons to do it this way:
>
> * If you ever change the type that `p' points to, it's not
> necessary to change the malloc() call as well.

A better solution would be:

typedef int T;
T* p = (T*)malloc(128*sizeof(T));

> This is more of a problem in a large program
> but it's still convenient in a small one.
>
> * Taking the size of an object makes writing the statement
> less error-prone. You can verify that the sizeof syntax is
> correct without having to look at the declaration.

On Mon, 1 Dec 2003 19:00:18 UTC, Lionel Valero
<> wrote:

> I forgto the headers :
> #include <stdio.h>
> #include <sys/types.h>
> #include <time.h>
>

You forgot to include stdlib.h again
> Lionel Valero wrote:

> > ka = (int *) malloc(nka * sizeof(int));

And this cast hides the error that you forgot to include the header in
redhat linux.
Casting the result from a function that returns void* is always an
error.

--
Tschau/Bye
Herbert

To buy eComStation 1.1 in germany visit http://www.pc-rosenau.de