设计一个类，用自己的成员函数重载运算符，使对整型的运算符=、+、-、*、/ 适用于分数运算。要求： （1）输出结果是最简分数（可以是带分数）； （2）分母为1，只输出分子。 （3）用友元函数重载运算符，使对整型的运算符=、+、-、*、/ 适用于分数运算。

以下是一个实现上述要求的分数类Fraction：

#include <iostream>

using namespace std;

int gcd(int a, int b) {
    return b == 0 ? a : gcd(b, a % b);
}

class Fraction {
public:
    Fraction(int num = 0, int den = 1) {
        int d = gcd(num, den);
        numerator = num / d;
        denominator = den / d;
        if (denominator < 0) {
            numerator = -numerator;
            denominator = -denominator;
        }
    }

    Fraction& operator=(int num) {
        numerator = num;
        denominator = 1;
        return *this;
    }

    Fraction operator+(const Fraction& other) const {
        int num = numerator * other.denominator + other.numerator * denominator;
        int den = denominator * other.denominator;
        return Fraction(num, den);
    }

    Fraction operator-(const Fraction& other) const {
        int num = numerator * other.denominator - other.numerator * denominator;
        int den = denominator * other.denominator;
        return Fraction(num, den);
    }

    Fraction operator*(const Fraction& other) const {
        int num = numerator * other.numerator;
        int den = denominator * other.denominator;
        return Fraction(num, den);
    }

    Fraction operator/(const Fraction& other) const {
        int num = numerator * other.denominator;
        int den = denominator * other.numerator;
        return Fraction(num, den);
    }

    friend Fraction operator+(int num, const Fraction& frac) {
        return Fraction(num) + frac;
    }

    friend Fraction operator-(int num, const Fraction& frac) {
        return Fraction(num) - frac;
    }

    friend Fraction operator*(int num, const Fraction& frac) {
        return Fraction(num) * frac;
    }

    friend Fraction operator/(int num, const Fraction& frac) {
        return Fraction(num) / frac;
    }

    friend ostream& operator<<(ostream& os, const Fraction& frac) {
        if (frac.denominator == 1) {
            os << frac.numerator;
        } else if (abs(frac.numerator) >= frac.denominator) {
            int integer = frac.numerator / frac.denominator;
            int num = abs(frac.numerator) % frac.denominator;
            if (num == 0) {
                os << integer;
            } else {
                os << integer << " " << num << "/" << frac.denominator;
            }
        } else {
            os << frac.numerator << "/" << frac.denominator;
        }
        return os;
    }

private:
    int numerator;
    int denominator;
};

这个类重载了运算符=、+、-、*、/，并且定义了友元函数来支持整数和分数之间的运算。在输出时，它会将分数转换为最简分数或带分数的形式。

下面是一个例子，展示了如何使用Fraction类：

int main() {
    Fraction a(1, 2);
    Fraction b(3, 4);
    Fraction c = a + b;
    cout << c << endl; // 输出 5/4
    c = a - b;
    cout << c << endl; // 输出 -1/4
    c = a * b;
    cout << c << endl; // 输出 3/8
    c = a / b;
    cout << c << endl; // 输出 2/3
    Fraction d = 2 + a;
    cout << d << endl; // 输出 5/2
    d = 2 - a;
    cout << d << endl; // 输出 3/2
    d = 2 * a;
    cout << d << endl; // 输出 1
    d = 2 / a;
    cout << d << endl; // 输出 4
    return 0;
}