如何使用 c++ 中的类编写有理分数

How to write Rational Fractions using classes in c++

本文关键字：何使用 c++      更新时间：2023-10-16

我必须实现Rational类才能得到有理分数。header.h文件由我的老师提供，所以我必须跟进。我还必须在Rational::Rational(const Rational& cRational)函数中编写复制构造函数，以便可以复制object。我已经编写了代码，但在输出中添加分数是错误的。谁能帮我弄清楚这个？我的编码有什么问题，特别是在Rational::addition(const Rational &a)或我该如何解决它？

输出：

Begin Rational Class Tests
Testing default constructor: 1/1
Testing std constructor: 1/2
Testing copy constructor: 1/2
Testing addition: 4/4 + 1/2 = 4/4    // it should be 1/2 + 1/2 = 4/4

主要功能：

int main()
{
cout << "Begin Rational Class Testsnn";
cout<<"Testing default constructor: ";
Rational n1;
n1.printRational();
cout << endl << endl;
cout<<"Testing std constructor: ";
Rational n2(1,2);
n2.printRational();
cout << endl << endl;
cout<<"Testing copy constructor: ";
Rational n3(n2);
n3.printRational();
cout << endl << endl;
cout<<"Testing addition: ";
n1 = n2.addition(n3);
n2.printRational();
cout <<" + ";
n3.printRational();
cout <<" = ";
n1.printRational();
cout << endl << endl;
}

头文件：

class Rational {
public:
Rational();  // default constructor
Rational(int, int); //std (initialisation) constructor
Rational(const Rational&); //copy constructor
Rational addition(const Rational &);
void printRational();
private:
int numerator;
int denominator;
};

我的程序：

//default constructor
Rational::Rational() 
{
numerator = 1;
denominator = 1;
}
//initialize constructor
Rational::Rational(int n, int d)
{
numerator = n;
if (d==0) 
{
cout << "ERROR: ATTEMPTING TO DIVIDE BY ZERO" << endl;
exit(0); // will terminate the program if division by 0 is attempted
}
else
denominator = d;
}
//copy constructor
Rational::Rational(const Rational& cRational)
{
numerator = cRational.numerator;
denominator = cRational.denominator;
}
//addition
Rational Rational::addition(const Rational &a)
{
numerator = numerator * a.denominator + a.numerator * denominator;
denominator = denominator * a.denominator;
return Rational(numerator,denominator);
}
void Rational::printRational()
{
cout << numerator << "/" << denominator ;
}

你的加法函数正在修改*this的成员变量，这会导致奇怪的事情发生。
更合适的原型是

Rational addition(const Rational &) const;

因为这会让编译器告诉您您正在做一些奇怪的事情。

您可以使用局部变量而不是分配给成员，也可以完全不使用中间变量：

Rational Rational::addition(const Rational &a)
{
return Rational(numerator * a.denominator + a.numerator * denominator, 
denominator * a.denominator);
}

只需在 addition(( 中为分子和分母的新值创建具有不同名称的新变量，有点像这样......

int n, d;  //you could use better names
n = numerator * a.denominator + a.numerator * denominator;
d = denominator * a.denominator;
return Rational(n, d);

我检查了一下，这在这里有效。

通常，不要对同一作用域中的两个变量使用相同的名称。

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