Thread: Problem with GMP

Hello guys, i am trying to solve Project eular problem-20 :"Find the sum of the digits in the number 100!".So i downloaded and included gmp libary for big integer.This is my code:

Code:

#include <stdio.h>
#include <mpir.h>
int main()
{
unsigned long s=0;

mpz_t result;
mpz_init (result);
mpz_fac_ui (result,10);
while(result>0)   //untill here everything works fine
{
        s+=mpz_tdiv_r_ui (result, result, 10); 
        mpz_tdiv_q_ui (result, result, 10); 
}
printf ("%lu", s);
return 0;
}

I am definetly having problems with while loop and instructions in it,and i just dont know how to solve it. The reason why i used 10!, its just a test.
Thank you for your time.

Originally Posted by oogabooga

You can't use any "normal" operations on mpz_t's. So you'll have to replace result>0 with whatever function GMP has for that.

Actually, GMP is overkill for this since it basically just does it for you. You should do it yourself with plain old C.

Thank you i did it , and also i didnt need two insructions only one

Code:

s+=mpz_tdiv_q_ui (result,result, 10);

.
And instead while i did for loop that goes from 1 to 300 (i suppose that number is not longer) , but still i should sreach and find special function in gmp for result>0.

Looks like this is what you need:
int mpz_cmp_ui (mpz_t op1, unsigned long int op2) Macro
Compare op1 and op2. Return a positive value if op1 > op2, zero if op1 = op2, or a negative value if op1 < op2.

Code:

while (mpz_cmp_ui(result,0) > 0)

Originally Posted by oogabooga

Looks like this is what you need:
int mpz_cmp_ui (mpz_t op1, unsigned long int op2) Macro
Compare op1 and op2. Return a positive value if op1 > op2, zero if op1 = op2, or a negative value if op1 < op2.

Code:

while (mpz_cmp_ui(result,0) > 0)

How did i miss that? Thank you, it works like a charm