复数

代码如下： （只写了一部分代码，其他懒得写，也没有使用模板类）
class Complex {
public:
double real, imag;

    Complex(double real = 0, double imag = 0) {
        this->real = real;
        this->imag = imag;
    }

    Complex operator +(Complex c){
        Complex res(real + c.real, imag + c.imag);
        return res;
    }

    Complex operator -(Complex c) {
        Complex res(real - c.real, imag - c.imag);
        return res;
    }

    Complex operator * (Complex c) {
        double new_real = (real * c.real - imag * c.imag);
        double new_imag = (real * c.imag + imag * c.real);
        Complex res(new_real, new_imag);
        return res;
    }

    Complex operator ~ () {
        Complex res(real, -imag);
        return res;
    }

    friend ostream& operator << (ostream &out, Complex c) {
        out << c.real;
        if (c.imag > 0) {
            out << '+';
        }
        if (c.imag != 0) {
            out << c.imag << "im";
        }
        return out;
    }
};

定义用其他函数生成该类的构造函数有利于这个类地更广泛地应用。