On Oct 21, 2009, at 2:31 PM, Denis Kirjanov wrote:
Just did a comparison test but it tells me otherwise. But I'm not
sure if the test case if correct, can someone improve it?
On a 64bit CentOS:
[root@yyan ~]# more test.c
#include <stdio.h>
int main ()
{
printf ("%d\n", sizeof(int));
return 0;
}
[root@yyan ~]# gcc test.c
[root@yyan ~]# ./a.out
4
[root@yyan ~]# uname -a
Linux yyan.pmlab.com 2.6.18-128.el5 #1 SMP Wed Jan 21 10:41:14 EST
2009 x86_64 x86_64 x86_64 GNU/Linux
[root@yyan ~]#
Yeah, sizeof(int) is 4, but what about sizeof(void*) ?)
Right, here's the real deal:
simonmac:coding yansimon$ uname -a
Darwin simonmac.local 9.8.0 Darwin Kernel Version 9.8.0: Wed Jul 15
16:55:01 PDT 2009; root:xnu-1228.15.4~1/RELEASE_I386 i386
simonmac:coding yansimon$ more test.c
#include <stdio.h>
int main ()
{
printf ("sizeof int is %d\n", sizeof(int));
printf ("sizeof void* is %d\n", sizeof(void*));
return 0;
}
simonmac:coding yansimon$ gcc test.c
simonmac:coding yansimon$ ./a.out
sizeof int is 4
sizeof void* is 4
[root@yyan ~]# cat test.c
#include <stdio.h>
int main ()
{
printf ("sizeof int is %d\n", sizeof(int));
printf ("sizeof void* is %d\n", sizeof(void*));
return 0;
}
[root@yyan ~]# gcc test.c
[root@yyan ~]# ./a.out
sizeof int is 4
sizeof void* is 8
[root@yyan ~]# uname -a
Linux yyan.pmlab.com 2.6.18-128.el5 #1 SMP Wed Jan 21 10:41:14 EST
2009 x86_64 x86_64 x86_64 GNU/Linux
On my Leopard: (Hopefully it's a 32bit OS as it shows)
simonmac:coding yansimon$ cat test.c
#include <stdio.h>
int main ()
{
printf ("%d\n", sizeof(int));
return 0;
}
simonmac:coding yansimon$ gcc test.c
simonmac:coding yansimon$ ./a.out
4
simonmac:coding yansimon$ uname -a
Darwin simonmac.local 9.8.0 Darwin Kernel Version 9.8.0: Wed Jul 15
16:55:01 PDT 2009; root:xnu-1228.15.4~1/RELEASE_I386 i386
simonmac:coding yansimon$
Lastly, How are "sizes" of compiler / OS / processor inter related?
Here is my understanding. A 32 bit processor can only be running a 32
bit OS.
No ... 32 bit OS can run anything <= 32 bit
A 64 bit processor may run a 32 or a 64 bit OS.
yes thats right !
A 32 bit
compiler genrates code only to be run on a 32 bit OS; ditto for 64
bit
Not sure about this let others have their say !
Is this right?
Yes it is, unlike the cross-compiler.
--
Regards,
Denis
--
益牙
http://www.google.com/profiles/simonyanix
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