How to use GMP.

[juneco@quartz.ocn.ne.jp]

Tomonori Kouya here.

Your program is not standard, I think. If you get correct results only, 
how about the following list ?

#include <stdio.h>
#include <gmp.h>
#include <stdarg.h>
//#include <obstack.h>

main()
{
        mpz_t bbbbb, aaaaa;

        mpz_init_set_str(bbbbb,"2147483647", 10);

        mpz_init(aaaaa);
        mpz_mul_ui(aaaaa, bbbbb, 3);

        gmp_printf("bbbbb=%Zd\n",bbbbb);
        gmp_printf("aaaaa=%Zd\n",aaaaa);

        mpz_clear(bbbbb);
        mpz_clear(aaaaa);
}

Results on Pentium 4 PC with Windows XP and GMP 4.1.2:

$ ./a
bbbbb=2147483647
aaaaa=6442450941

Hashida <jhashida@fls.fujitsu.com>さん：
> Hi
> 
> I am a beginner for GMP and not good at C.
> I can't understand how to use GMP very well.
> For example, in arithmetic of 231*3
> I wrote the following C program.
> 
> #include <stdio.h>
> #include <gmp.h>
> #include <stdarg.h>
> #include <obstack.h>
> 
> main()
> {
>         MP_INT *bbbbb=(MP_INT *)malloc(50);
>         MP_INT aaaaa;
> 
>         bbbbb->_mp_d=(mp_limb_t *)malloc(10);
> 
>         mpz_init_set_ui(bbbbb,2147483647);
>         printf("bbbbb->_mp_alloc=%d\n",bbbbb->_mp_alloc);
>         printf("bbbbb->_mp_size=%d\n",bbbbb->_mp_size);
>         printf("*(bbbbb->_mp_d)=%d\n",*(bbbbb->_mp_d));
>         mpz_init(&aaaaa);
>         mpz_mul_ui(&aaaaa, bbbbb, 3);
>         printf("aaaaa._mp_alloc=%d\n",aaaaa._mp_alloc);
>         printf("aaaaa._mp_size=%d\n",aaaaa._mp_size);
>         printf("*(aaaaa._mp_d)=%d\n",*(aaaaa._mp_d));
> 
> }
> 
> The result of the execution of this program is as follows.
> 
> bbbbb->_mp_alloc=1
> bbbbb->_mp_size=1
> *(bbbbb->_mp_d)=2147483647
> aaaaa._mp_alloc=2
> aaaaa._mp_size=2
> *(aaaaa._mp_d)=2147483645
> 
> 231*3 is 6442450944 in decimal system.
> 
> Please teach me how to recognize 6442450944 from the above result.
> Simply the way of the usage of "printf" may be bad, but I don't know.
> 
> Thanks.
> 
> Hashida
>