c++ - 具有为有理数对自行设计的类的 C++ 程序无法按预期工作

Question

我对下面的代码有疑问。它现在不执行任何功能......既不加也不减，也不除也不乘。

任何帮助将不胜感激......我需要解释......这样我才能理解并克服它：D

#include <iostream>
using namespace std;

// Class Definitions

class RationalNumber
{
public:
     RationalNumber(int, int, int, int);                    
     RationalNumber operator+(RationalNumber);
     RationalNumber operator-(RationalNumber);
     RationalNumber operator*(RationalNumber);
     RationalNumber operator/(RationalNumber);
     RationalNumber operator<(RationalNumber);
     RationalNumber operator>(RationalNumber);
     RationalNumber operator<=(RationalNumber);
     RationalNumber operator>=(RationalNumber);
     RationalNumber operator==(RationalNumber);
     RationalNumber operator!=(RationalNumber);
private:
     int numerator;
     int denominator;
     int numerator2;
     int denominator2;

};  // end RationalNumber class


// RationalNumber class member-function definitions
RationalNumber::RationalNumber(int num, int denom, int num2, int denom2)
{
     numerator = num;
     denominator = denom;
     numerator2 = num2;
     denominator2 = denom2;

//for first fraction
     if (denominator == 0 || denominator < 0)
          cout << "ERROR:Denominator can not be zero or less than zero." << "\n";

     else
          //Reduces the fraction to lowest terms.
     {
          int i = numerator > denominator ? numerator : denominator;

          while(i > 1)
          {
               if(numerator % i == 0 && denominator % i == 0)  
               {
               numerator /= i;
               denominator /= i;
               }
               --i;
          }

     }

     cout << "Simplified fraction one is: " << numerator << " / "
        << denominator << "\n";

//For second fraction
     if (denominator2 == 0 || denominator2 < 0)
          cout << "ERROR:Denominator can not be zero or less than zero" << "\n";
     else
          //Reduces the fraction to lowest terms.
     {
          int j = numerator2 > denominator2 ? numerator2 : denominator2;

          while(j > 1)
          {
               if(numerator2 % j == 0 && denominator2 % j == 0)  
               {
               numerator2 /= j;
               denominator2 /= j;
               }
               --j;
          }

     }
     cout << "Simplified fraction two is: " << numerator2 << " / "
        << denominator2 << "\n";

}

// addition operator
RationalNumber RationalNumber::operator+(RationalNumber a)
{
      RationalNumber temp=RationalNumber(1,2,3,4);
      temp.numerator = numerator + a.numerator;
      temp.denominator = denominator + a.denominator;
      temp.numerator2 = numerator2 + a.numerator2;
      temp.denominator2 = denominator2 + a.denominator2;
      return temp;
}

// subtraction operator
RationalNumber RationalNumber::operator-(RationalNumber a)
{
     RationalNumber temp=RationalNumber(1,2,3,4);
      temp.numerator = numerator - a.numerator;
      temp.denominator = denominator - a.denominator;
      temp.numerator2 = numerator2 - a.numerator2;
      temp.denominator2 = denominator2 - a.denominator2;
      return temp;
}

// multiplication operator
RationalNumber RationalNumber::operator*(RationalNumber a)
{
      RationalNumber temp=RationalNumber(1,2,3,4);
      temp.numerator = numerator * a.numerator;
      temp.denominator = denominator * a.denominator;
      temp.numerator2 = numerator2 * a.numerator2;
      temp.denominator2 = denominator2 * a.denominator2;
      return temp;
}

// division operator
RationalNumber RationalNumber::operator/(RationalNumber a)
{
      RationalNumber temp=RationalNumber(1,2,3,4);
      temp.numerator = numerator / a.numerator;
      temp.denominator = denominator / a.denominator;
      temp.numerator2 = numerator2 / a.numerator2;
      temp.denominator2 = denominator2 / a.denominator2;
      return temp;
}

int main()
{

     int top;
     int bot;
     int top2;
     int bot2;

     cout << "Please enter the Numerator for fraction one: \n";
     cin >> top;
     cout << "Please enter the Denominator for fraction one: \n";
     cin >> bot;
     cout << "Please enter the Numerator for fraction two: \n";
     cin >> top2;
     cout << "Please enter the Denominator for fraction two: \n";
     cin >> bot2;

     RationalNumber A(top, bot, top2, bot2);
     return 0;

}

Answer 1

通过声明RationalNumber(int, int, int, int)，您将自动删除默认构造函数，即不再可能通过调用不带参数的构造函数来创建类的实例。

换句话说，

RationalNumber number;

不再可能。你需要说

RationalNumber number(1,2,3,4);.

如果您希望能够使用默认构造函数创建实例，那么除了另一个构造函数之外，您还需要定义一个：

RationalNumber()
{
    // Initialization
}

Answer 2

重新定义您的运营商：

RationalNumber RationalNumber::operator+(RationalNumber a)
{
      return RationalNumber(
          numerator + a.numerator,
          denominator + a.denominator,
          numerator2 + a.numerator2,
          denominator2 + a.denominator2);
}

这样可以避免创建导致您悲伤的无参数临时性。它还帮助编译器利用返回值优化 (RVO)。

Answer 3

我会快速拍摄一下……</p>

#include <utility>

struct ratio {
    int numerator;
    int denominator;

    explicit ratio( int n = 0, int d = 1 )
        : numerator( n ), denominator( d ) { }

    ratio operator - () const {
        ratio x( * this );
        x.numerator = - x.numerator;
        return x;
    }

    ratio operator + () const
        { return *this; }
};

void reduce( ratio &x ) {
    int larger = x.numerator, smaller = x.denominator;
    if ( larger < smaller ) std::swap( larger, smaller );
    while ( int rem = larger % smaller ) {
        larger = smaller;
        smaller = rem;
    }
    x.numerator /= smaller;
    x.denominator /= smaller;
}


ratio &operator += ( ratio &l, ratio const &r ) {
    l.numerator = l.numerator * r.denominator
                + r.numerator * l.denominator;
    l.denominator *= r.denominator;
    reduce( l );
    return l;
}

ratio &operator -= ( ratio &l, ratio const &r )
    { return l += - r; }

ratio &operator *= ( ratio &l, ratio const &r ) {
    l.numerator *= r.numerator;
    l.denominator *= r.denominator;
    reduce( l );
    return l;
}

ratio &operator /= ( ratio &l, ratio const &r ) {
    l.numerator *= r.denominator;
    l.denominator *= r.numerator;
    reduce( l );
    return l;
}

运算符+, -, *,/的规范定义

Answer 4

您的类没有采用零参数的构造函数。因此，下面的代码：

class object=class();

正在尝试使用不存在的构造函数。您必须编写一个带零参数的构造函数（显式地或通过为另一个构造函数的参数提供所有默认值），或者您必须在构造时提供值：

class object(1, 2, 3, 4);
class object2 = class(1, 2, 3, 4);

Answer 5

现在的问题是......它没有执行任何添加或任何其他功能......程序运行完美但不知何故我得到了附加和其他功能工作

谢谢

#include <iostream>
using namespace std;

// Class Definitions

class RationalNumber
{
public:
     RationalNumber(int, int, int, int);                    
     RationalNumber operator+(RationalNumber);
     RationalNumber operator-(RationalNumber);
     RationalNumber operator*(RationalNumber);
     RationalNumber operator/(RationalNumber);
     RationalNumber operator<(RationalNumber);
     RationalNumber operator>(RationalNumber);
     RationalNumber operator<=(RationalNumber);
     RationalNumber operator>=(RationalNumber);
     RationalNumber operator==(RationalNumber);
     RationalNumber operator!=(RationalNumber);
private:
     int numerator;
     int denominator;
     int numerator2;
     int denominator2;

};  // end RationalNumber class


// RationalNumber class member-function definitions
RationalNumber::RationalNumber(int num, int denom, int num2, int denom2)
{
     numerator = num;
     denominator = denom;
     numerator2 = num2;
     denominator2 = denom2;

//for first fraction
     if (denominator == 0 || denominator < 0)
          cout << "ERROR:Denominator can not be zero or less than zero." << "\n";

     else
          //Reduces the fraction to lowest terms.
     {
          int i = numerator > denominator ? numerator : denominator;

          while(i > 1)
          {
               if(numerator % i == 0 && denominator % i == 0)  
               {
               numerator /= i;
               denominator /= i;
               }
               --i;
          }

     }

     cout << "Simplified fraction one is: " << numerator << " / "
        << denominator << "\n";

//For second fraction
     if (denominator2 == 0 || denominator2 < 0)
          cout << "ERROR:Denominator can not be zero or less than zero" << "\n";
     else
          //Reduces the fraction to lowest terms.
     {
          int j = numerator2 > denominator2 ? numerator2 : denominator2;

          while(j > 1)
          {
               if(numerator2 % j == 0 && denominator2 % j == 0)  
               {
               numerator2 /= j;
               denominator2 /= j;
               }
               --j;
          }

     }
     cout << "Simplified fraction two is: " << numerator2 << " / "
        << denominator2 << "\n";

}

// addition operator
RationalNumber RationalNumber::operator+(RationalNumber a)
{
      RationalNumber temp=RationalNumber(1,2,3,4);
      temp.numerator = numerator + a.numerator;
      temp.denominator = denominator + a.denominator;
      temp.numerator2 = numerator2 + a.numerator2;
      temp.denominator2 = denominator2 + a.denominator2;
      return temp;
}

// subtraction operator
RationalNumber RationalNumber::operator-(RationalNumber a)
{
      RationalNumber temp=RationalNumber(1,2,3,4);
      temp.numerator = numerator - a.numerator;
      temp.denominator = denominator - a.denominator;
      temp.numerator2 = numerator2 - a.numerator2;
      temp.denominator2 = denominator2 - a.denominator2;
      return temp;
}

// multiplication operator
RationalNumber RationalNumber::operator*(RationalNumber a)
{
      RationalNumber temp=RationalNumber(1,2,3,4);
      temp.numerator = numerator * a.numerator;
      temp.denominator = denominator * a.denominator;
      temp.numerator2 = numerator2 * a.numerator2;
      temp.denominator2 = denominator2 * a.denominator2;
      return temp;
}

// division operator
RationalNumber RationalNumber::operator/(RationalNumber a)
{
      RationalNumber temp=RationalNumber(1,2,3,4);
      temp.numerator = numerator / a.numerator;
      temp.denominator = denominator / a.denominator;
      temp.numerator2 = numerator2 / a.numerator2;
      temp.denominator2 = denominator2 / a.denominator2;
      return temp;
}

int main()
{

     int top;
     int bot;
     int top2;
     int bot2;

     cout << "Please enter the Numerator for fraction one: \n";
     cin >> top;
     cout << "Please enter the Denominator for fraction one: \n";
     cin >> bot;
     cout << "Please enter the Numerator for fraction two: \n";
     cin >> top2;
     cout << "Please enter the Denominator for fraction two: \n";
     cin >> bot2;

     RationalNumber A(top, bot, top2, bot2);
     return 0;

}