浮点异常错误

Question

This program compiles fine, but it returns a message "Floating Point Exception" when I run it. I've looked at other threads and the problem appears to be dividing by 0, but I have looked over the program and there's no division by zero in my entire program. I even used the absolute value function in case.

By the way, the program is meant to reduce fractions.

Example input: 6 12 , representing the fraction 6/12
Expected output: 1/2

#include <stdio.h>

/*declaring variables*/
int num1, num2, num1b, num2b, gcd, x;
int higher, lower, higher_2, lower_2;

/*declaring functions*/
int find_gcd(int num1, int num2);
void reduce(int numerator, int denominator, int *reduced_numerator, int *reduced_denominator);

int main(void)
{
    do
    {
        printf("enter 2 numbers:  ");
        scanf("%d %d", &num1, &num2);
        reduce(higher, lower, &higher_2, &lower_2);
        printf("enter 0 to end program and any number continue: \n");
        scanf("%d", &x);
    } while(x != 0);

    return 0;
}

void reduce(int numerator, int denominator, int *reduced_numerator, int *reduced_denominator)
{
    num1=numerator;
    num2=denominator;

    gcd =find_gcd(numerator, denominator);

    *reduced_numerator = (numerator/abs(gcd));
    *reduced_denominator = (denominator/abs(gcd));

    printf("The GCD is %d/%d\n", *reduced_numerator, *reduced_denominator); 
}

int find_gcd(int m, int n)
{
    while (n != 0) {
        int remainder = m % n;
        m = n;
        n = remainder;
    }
    return m;
}

Answer 1

Your main problem is that you are not passing your input values num1 and num2 into your reduce() function. Instead you are passing in the global variables higher and lower . You didn't assign any values to them, but global variables are always initialized to 0 by default. Therfore, you run into the exception, because in reduce() you divide 0 by 0. You can verify that with a debugger.

If I change your main() as follows, then your code is at least working for your test case with 6 and 12 as input:

int main(void)
{
    do
    {
        printf("enter 2 numbers:  ");
        scanf("%d %d", &num1, &num2);
        reduce(num1, num2, &higher_2, &lower_2);
        printf("enter 0 to end program and any number continue: \n");
        scanf("%d", &x);
    } while(x != 0);

    return 0;
}

Output:

enter 2 numbers: 6
12
The GCD is 1/2
enter 0 to end program and any number continue:

---

As indicated in the comments you should also get rid of global and spurious variables. Therefore, you should first delete the following lines in your code:

/*declaring variables*/
int num1, num2, num1b, num2b, gcd, x;
int higher, lower, higher_2, lower_2;

Then let your main() function start the following way:

int main(void)
{
    int num1, num2, higher_2, lower_2, x;
    ...
}

And your reduce() function should read like this:

void reduce(int numerator, int denominator, int *reduced_numerator, int *reduced_denominator)
{
    int gcd = find_gcd(numerator, denominator);

    *reduced_numerator = (numerator/abs(gcd));
    *reduced_denominator = (denominator/abs(gcd));

    printf("The GCD is %d/%d\n", *reduced_numerator, *reduced_denominator); 
}

So far, you don't use your variables higher_2 and lower_2 in the main() function, but I guess you plan to do so. If not, you can also get rid of them together with parameters 3 and 4 of your reduce() function.

---

There is another issue with the code you provided (thanks to @user3629249 for pointing it out): You are missing an include for the abs() function. So you need to add the line #include <stdlib.h> at the beginning of your code ( include <math.h> will also so the trick, as well as include <Windows.h> on Windows).