友元函数实现复数类操作（P132）

#include<iostream>

using namespace std;

class myComplex
{
private:
double real,imag;
public:
myComplex();
myComplex(double r,double i);
friend myComplex addCom(myComplex c1,myComplex c2);
friend void outCom(myComplex c);
};

myComplex::myComplex()
{
real = 0;
imag = 0;
}

myComplex::myComplex(double r,double i)
{
real = r;
imag = i;
}

myComplex addCom(myComplex c1,myComplex c2)
{
return myComplex(c1.real + c2.real,c1.imag + c2.imag);
}

void outCom(myComplex c)
{
cout<<"("<<c.real<<","<<c.imag<<")";
}

int main()
{
myComplex c1(1,2),c2(3,4),res;
res = addCom(c1,c2); //通过友元函数不通过类对象
outCom(c1);
cout<<"+";
outCom(c2);
cout<<"=";
outCom(res);
cout<<endl;
return 0;
}