复数类型--class complex

class complex{

    double re,im;  //representation:two doubles

public:

    complex(double r,double i):re{r},im{i}{}          //construct complex from two scalars

    complex(double r):re{r},im{0}{}                      //construct complex from one scalar

    complex():re{0},im{0}{}                                  //default complex:{0,0}

    

    double real() const { return re;}

    void real(double d) { re=d;}

    double imag() const { return im;}

    void imag(double d) { im=d;}

 

    complex& operator+=(complex z) { re+=z.re,im+=z.im; return *this;}      //add to re and im and return the result

    complex& operator-=(complex z) { re-=z.re,im-=z.im; return *this;}

    complex& operator*=(complex);            //defined out-of-class somewhere

    complex& operator/=(complex);            //defined out-of-class somewhere

};

complex operator+(complex a,complex b) { return a+=b;}

complex operator-(complex a, complex b) { return a-=b;}

complex operator-(complex a) { return {-a.real(),-a.imag()};}    //unary minus

complex operator*(complex a, complex b) { return a*=b;}

complex operator/(complex a, complex b) { return a/=b;}

 

bool operator==(complex a, complex b)     //equal

{

    return a.real()==b.real() && a.imag()==b.imag();

}

bool operator!=(complex a, complex b)    //not equal

{

    return !(a==b);

}

complex sqrt(complex);

//...

用法如下：

void f(complex z)

{

    complex a{2.3};                      //construct {2.3,0.0} from 2.3

    complex b{1/a};

    complex c{a+z*complex{1,2.3}};

    //...

    if(c!=b)

        c=-(b/a)+2*b;

}