Question

我之前写过一个程序，它将两个分数组合在一起并打印输出，我知道这很简单。我最初使用结构实现了程序，现在我正在尝试使用类重新实现它，不是那么简单我猜...问题是每当我打印输出时它返回为零（对于分母为双零，无论我输入什么数字，我都不知道为什么会这样做。

Sample output:
Enter First Numerator: 1
Enter First Denominator: 2
Enter Second Numerator: 1
Enter Second Denominator: 4
-------------------------
0/00 + 0/00 = 0/00

请查看我的代码并告诉我问题是什么？

#include <iostream>
using namespace std;

class Fraction
{
private:
    int numerator;
    int denominator;
public:
    Fraction()
    {
        numerator = 0;
        denominator = 0;
    }
public:
    void set(int n, int d) {n = numerator; d = denominator;};
    int getNumerator() {return numerator;};
    int getDenominator() {return denominator;};
    Fraction addTo(Fraction &frac2, Fraction& frac3);
    int print() { cout << numerator << "/" << denominator; return 0;};
};
//Adds the value of the Fraction with the attached "addTo" method with the value of a second   specified Fraction and assigns the result to a third specified Fraction.
Fraction Fraction::addTo(Fraction& frac2, Fraction& addedTo)
{
    frac2.numerator = (numerator * frac2.denominator) + (denominator * frac2.numerator);
    frac2.denominator = (denominator * frac2.denominator);
    frac2.numerator = addedTo.numerator;
    frac2.denominator = addedTo.denominator;
    return addedTo;
}

int main()
{
Fraction frac1, frac2, frac3;
int n1, n2, d1, d2;

//Prompts the user for data and then assigns it to the correct variables.
cout << "Enter First Numerator: ";
cin >> n1;

cout << "Enter First Denominator: ";
cin >> d1;

cout << "Enter Second Numerator: ";
cin >> n2;

cout << "Enter Second Denominator: ";
cin >> d2;

frac1.set(n1, d1);
frac2.set(n2, d2);

frac1.addTo(frac2, frac3);

//Formats output.
cout<< "-------------------------\n"
    << frac1.print() << " + " << frac2.print()<< " = " << frac3.print() << endl;
cout << "\n";

return 0;
}

Answer 1

你在这里弄错了：

int print() { cout << numerator << "/" << denominator; /* why to hell this method returns 0?! */ return 0;};

就这样写：

void print() { cout << numerator << "/" << denominator; }; // this method doesn't need to return any value

你在这里犯了一个错误：

//Formats output.
cout<< "-------------------------\n"
<< frac1.print() << " + " << frac2.print()<< " = " << frac3.print() << endl;
cout << "\n";

您可以简单地写一下：

// Formats output
frac1.print();
std::cout << " + ";
frac2.print();
std::cout << " = ";
frac3.print();

是的，当然你可以尝试创建将fraction返回为字符串的方法，但是你必须将int转换为string然后使用stringstream，所以我的想法更容易。

<强> @EDIT

你没有在这里设置分子和分母的值：

//Prompts the user for data and then assigns it to the correct variables.
cout << "Enter First Numerator: ";
cin >> n1;

cout << "Enter First Denominator: ";
cin >> d1;

cout << "Enter Second Numerator: ";
cin >> n2;

cout << "Enter Second Denominator: ";
cin >> d2;

你必须这样写：

//Prompts the user for data and then assigns it to the correct variables.
cout << "Enter First Numerator: ";
cin >> n1;
frac1.numerator = n1;

cout << "Enter First Denominator: ";
cin >> d1;
frac1.denominator = d1;

cout << "Enter Second Numerator: ";
cin >> n2;
frac2.numerator = n2;

cout << "Enter Second Denominator: ";
cin >> d2;
frac2.denominator = d2;

<强> @ EDIT2

我刚刚发现了你犯的一个新错误。你必须写这样的add方法：

//Adds the value of the Fraction with the attached "addTo" method with the value of a second   
specified Fraction and assigns the result to a third specified Fraction.
Fraction Fraction::addTo(Fraction& frac2, Fraction& addedTo)
{
    addedTo.numerator = (numerator * frac2.denominator) + (denominator * frac2.numerator);
    addedTo.denominator = (denominator * frac2.denominator);
    // frac2.numerator = addedTo.numerator; // this line was a mistake because you tried to set result's numerator again
    // frac2.denominator = addedTo.denominator; // the same as above
    return addedTo;
}

使用类添加分数（错误的输出）

1 个答案: