how to check if there is a division by zero in c

Question

#include<stdio.h>
void function(int);

int main()
{
     int x;

     printf("Enter x:");
     scanf("%d", &x);

function(x);

return 0;
}

void function(int x)
{
    float fx;

    fx=10/x;

    if(10 is divided by zero)// I dont know what to put here please help
        printf("division by zero is not allowed");
    else
        printf("f(x) is: %.5f",fx);

}

Answer 1

This should do it. You need to check for division by zero before performing the division.

void function(int x)
{
    float fx;

    if(x == 0) {
        printf("division by zero is not allowed");
    } else {
        fx = 10/x;
        printf("f(x) is: %.5f",fx);
    }
}

Answer 2

#include<stdio.h>
void function(int);

int main()
{
     int x;

     printf("Enter x:");
     scanf("%d", &x);

function(x);

return 0;
}

void function(int x)
{
    float fx;

    if(x==0) // Simple!
        printf("division by zero is not allowed");
    else
        fx=10/x;            
        printf("f(x) is: %.5f",fx);

}

Answer 3

With C99 you can use fetestexcept(2) et alia.

Answer 4

By default in UNIX, floating-point division by zero does not stop the program with an exception. Instead, it produces a result which is infinity or NaN. You can check that neither of these happened using isfinite.

x = y / z; // assuming y or z is floating-point
if ( ! isfinite( x ) ) cerr << "invalid result from division" << endl;

Alternately, you can check that the divisor isn't zero:

if ( z == 0 || ! isfinite( z ) ) cerr << "invalid divisor to division" << endl;
x = y / z;