Question

错误：＆gt;在244_w5_lab_prof.cpp中包含的文件中：11：0：
  Fraction.h：在成员函数'sict :: Fraction＆amp; sict :: Fraction :: operator *？＆gt;＆gt;＆gt;（sict :: Fraction）const'：
  Fraction.h：83：13：警告：引用局部变量'bb'返回[默认启用]
  Fraction.h：在成员函数'sict :: Fraction sict :: Fraction :: operator +（sict :: Fraction）'中：   Fraction.h：78：3：警告：控制到达非空函数的末尾[-Wreturn-type]
  在Fraction.cpp中包含的文件中：12：0：
  Fraction.h：在成员函数'sict :: Fraction＆amp; sict :: Fraction :: operator *＆gt;（sict :: Fraction）const'：
  Fraction.h：83：13：警告：引用局部变量'bb'返回[启用   默认]

    #ifndef SICT_Fraction_H__
    #define SICT_Fraction_H__

    #include <iostream>

    using namespace std;

    namespace sict{

       class Fraction{
       private:

        int num;                // Numerator
        int denom;              // Denominator

        int gcd();            // returns the greatest common divisor of num 
         and denom


  int max();        // returns the maximum of num and denom
  int min();        // returns the minimum of num and denom

        public:

    void reduce();     // simplifies a Fraction number by dividing the 
                       // numerator and denominator to their greatest common  
    divisor 

    Fraction();                             // default constructor
    Fraction(int n , int d=1);               // construct n/d as a Fraction 
    number

    void display() const {
        if (num < 0 || denom < -1)
            cout << "Invalid Fraction Object!";
        else if (denom == 1)
            cout << num;
        else {

            cout<<num<<"/"<< denom;
        } 
    }

    bool isEmpty() const;     

    // member operator functions

    // TODO: write the prototype of member operator+= function HERE
    Fraction & operator+=(const Fraction & f) {
        num = num*f.denom + denom*f.num;
        denom = denom*f.denom;
        reduce();
        return *this;

    }

    // TODO: write the prototype of member operator+ function HERE
    Fraction operator+(const Fraction & f) {
        if (!(this->denom == -1 || f.denom == -1))
        {
            Fraction temp;
            temp.num = num*f.denom + denom*f.num;
            temp.denom = denom*f.denom;
            temp.reduce();


            return temp;
        }

    }


    // TODO: write the prototype of member operator* function HERE
    Fraction & operator*(const Fraction & f) const {
        Fraction temp;
        temp.num = num*f.num;
        temp.denom = denom*f.denom;
        temp.reduce();

                return temp;
            }
       };
    };
    #endif

Answer 1

operator+仅在if语句为真时返回一些内容。它必须总是返回一些东西。

另一方面，operator*返回对局部变量temp的引用。它也应该按价值返回，例如operator+。

我不确定这些错误消息的含义

1 个答案: