C ++程序中的浮点异常

Question

#include <iostream>
#include <string>

using namespace std;
int main()
{
int num1, num2; // numerator                                                                                                                       
int den1, den2; // denominator                                                                                                                     

cin >> num1 >> den1 >> num2 >> den2;
if (den1<=0 || den2<=0)
cout << "problem could not be solved because denominator is zero and division by zero is        not defined" << endl;
else
if ((num1/den1)+(num2/den2))
cout << num1 << "/" << den1 << " + " << num2 << "/" << den2 << " = " << ((num1*den2)+  (den1*num2)) << "/" << (den1*den2) << endl;
else
  if ((num1/den1)-(num2/den2))
    cout << num1 << "/" << den1 << " - " << num2 << "/" << den2 << " = " <<    ((num1*den2)-(den1*num2)) << "/ " << (den1*den2) << endl;
else
  if ((num1/den1)*(num2/den2))
      cout << num1 << "/" << den1 << " * " << num2 << "/" << den2 << " = " <<     (num1*num2) << "/ " << (den1*den2) << endl;
    else
      if ((num1/den1)/(num2/den2) && num2 != 0)
        cout << num1 << "/" << den1 << " * " << num2 << "/" << den2 << " = " << (num1*den2) << "/ " << (den1*num2) << endl;
      else
        if ((num1/den1)/(num2/den2) && num2==0)
          cout << num1 << "/" << den1 << " * " << num2 << "/" << den2 << " could not be   solved because division by zero is not defined" << endl;\

 return 0;
 }

Hey guys I keep getting a floating exception when I run this program. I really can't figure out what the problem is. Help is extremely appreciated.

Answer 1

The problem is on these lines:

  if ((num1/den1)/(num2/den2) && num2 != 0)
    cout << num1 << "/" << den1 << " * " << num2 << "/" << den2 << " = " << (num1*den2) << "/ " << (den1*num2) << endl;
  else
    if ((num1/den1)/(num2/den2) && num2==0)
      cout << num1 << "/" << den1 << " * " << num2 << "/" << den2 << " could not be   solved because division by zero is not defined" << endl;\

The arguments to && are processed left-to-right. So if num2 is zero , you'll try to do the division before you test num2 != 0 ; so you need to perform the zero test first. You also need to test whether num2/den2 is zero, not just num2 , because the division could round down to zero even if num2 is not zero.

  if (num2/den2 != 0 && (num1/den1)/(num2/den2))
    cout << num1 << "/" << den1 << " * " << num2 << "/" << den2 << " = " << (num1*den2) << "/ " << (den1*num2) << endl;
  else
    cout << num1 << "/" << den1 << " * " << num2 << "/" << den2 << " could not be   solved because division by zero is not defined" << endl;