I think the problem is that you are mixing C++ and C. The mpz_t type is the
C data type, but you are trying to print it using the C++ cout function.
You want to use gmp_printf to print the C data types.
Another problem is you have not called mpz_init on any of the mpz_t's that
you created.
Bill.
On 22 December 2014 at 15:41, newcoder <hf.ba...@gmail.com> wrote:
> Hi,
>
> Thanks a lot for accepting my request to be a member of this group.
>
> This is my first attempt at using MPIR, so please excuse me if you find
> something silly :-)
>
> I was looking for a way to convert very large decimals numbers into binary
> using C. Since I did not find anything I thought of writing my own and
> started exploring MPIR. There might be some easier alternatives but I am
> using MPIR because I have to do some more maths on big numbers.
>
> What I am trying to do is input a decimal number and then convert this
> into binary. My program works fine till it find the number of bits
> required. However something is wrong in the way I am using the operations
> in the second last `for` loops, i.e:
>
> kb[i] = b % 2;
> b /= 2;
>
>
>
> This is what I am trying to convert into MPIR specific operations using
> mpz_mod() and mpz_cdiv_q(). What I have done is:
>
>
>
> mpz_t d;
> mpz_init (d);
> mpz_set_str (d, "2" , 10); //because I want to find (something)mod2 , d
> contains 2 now
>
> for (int i = nob; i > 0; i--)
> {
> mpz_mod(kb[i], b, d); // kb[i] = b % 2
> mpz_cdiv_q(b, b, d ); // b /= 2;
>
> }
>
> for (int i = nob; i > 0; i--)
> {
> cout<<kb[i]<<"\n";
> }
>
> This prints:
>
> Please, enter the decimal value: 100
> 7
> 0
> 0
> 1
> 1
> 1
> 0
> 0
> Press any key to continue . . .
>
> Which is wrong. The correct is 01100100
>
>
> Here is my code:
>
> int main()
>
> {
>
> mpz_t b ;
> size_t nob; //no. of bits will be here
>
> mpz_init (b); //Initialize
>
> char k[80]; //My decimal as an string will go here
>
> cout << "Please, enter the decimal value: ";
>
> cin.getline(k, sizeof k); //decimal value stored as string here
>
> mpz_set_str (b, k , 10); //transfer the string into b, assuming base
> 10
>
> nob = mpz_sizeinbase(b, 2); // find total number of bits in b
>
> cout<<nob<<"\n";
>
>
> mpz_t d;
> mpz_init (d);
> mpz_set_str (d, "2" , 10); //because I want to find (something)mod2
>
> mpz_t kb[80000]; //Array. will store my converted binary bits in kb
> for (int i = nob; i > 0; i--)
> {
> mpz_mod(kb[i], b, d); // implementing kb[i] = b % 2
> mpz_cdiv_q(b, b, d ); // b /= 2;
>
> }
>
> for (int i = nob; i > 0; i--)
> {
> cout<<kb[i]<<"\n";
> }
>
> return 0;
>
> }
>
>
>
> Can someone help me solve this issue?
>
> Thanks in advance for your valuable inputs.
>
>
>
> Note: I did not know that the request will be accepted so quickly, so
> posted it on stackoverflow also , which I can't delete now.
>
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