C ++程序中的浮點異常

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;
 }

嗨，伙計們，當我運行此程序時，我總是收到一個浮動異常。 我真的不知道是什么問題。 非常感謝您的幫助。

Answer 1

問題出在以下幾行：

  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;\

&&的參數從左到右處理。 因此，如果num2 zero ，則您將在測試num2 != 0之前嘗試進行除法； 因此您需要先執行零測試。 您還需要測試num2/den2是否為零，而不僅僅是num2 ，因為即使num2不為零，除法也可以舍入為零。

  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;