When I run this program I get an error called "Floating point exception"

Question

I get a floating point exception when running this program:

#include <stdio.h>

int check(int n)
{
    int ii=0;
    int jj=0;
    int sum_of_dividors=0;
    int sum_of_dividors2=0;
    for (ii=0;ii<n;ii++){
        for (jj=0;jj<ii;jj++){
            if(ii%jj==0)
            {
              sum_of_dividors=sum_of_dividors+jj;
            }
        }
        if(sum_of_dividors<n || ii<n){
            for (jj=0;jj<sum_of_dividors;jj++){
                if(sum_of_dividors%jj==0)
                {
                sum_of_dividors2=sum_of_dividors2+jj;
                }
            }
        if (sum_of_dividors2==ii){
            printf("%d and %d,",ii,sum_of_dividors);
        }
        }
    sum_of_dividors=0;
    sum_of_dividors2=0;
    }
}


int main()
{
    int n;

    printf("Enter n ");
    scanf("%d",&n);
    printf("%d",check(n));
}

The code's purpose is to check the closest pair of amicable numbers to the number (n) that the user have entered.

`int check(int n) { [ ..... ] }` Where is the `return` statement? `check` is supposed to return an `int`, but never returns anything. — abelenky, Apr 20 '18 at 12:18
You should've specified **where** that exception occurs. But assuming it was at the attempted modulo, if only everyone would just flag as a dupe of that instead of generating more unnecessary posts. — underscore_d, Apr 20 '18 at 12:19

score 1 · Answer 1 · answered Apr 20 '18 at 12:08

1

If you check with GDB, the problem is in the line

if(ii%jj==0)

You Can't Mod Zero?

answered Apr 20 '18 at 12:08

Jesferman

1,049
7
12

msc · Accepted Answer · 2018-04-20T12:17:02.953

1

C 6.5.5 [ISO/IEC 9899:2011] states:

The result of the / operator is the quotient from the division of the first operand by the second; the result of the % operator is the remainder. In both operations, if the value of the second operand is zero, the behavior is undefined.

So, modulo by zero invoked undefined behaviour in C.

edited Apr 20 '18 at 12:17

answered Apr 20 '18 at 12:09

msc

33,420
29
119
214

score 0 · Answer 3 · answered Apr 20 '18 at 12:14

0

You cannot mod % by 0 ! It will give undefined behavior !

answered Apr 20 '18 at 12:14

Bharadwaj

135
1
1
7

score 0 · Answer 4 · answered Apr 20 '18 at 12:29

You should apply for %, apart from the result, exactly the same constraints as /. Therefore, in C and C++, you can't mod by 0. If you want to have a behavior where X % 0 equals X, you'll have to check specifically for X to be equal to 0, and return it.

When I run this program I get an error called "Floating point exception"

4 Answers4