问答题

#include ＜ iostream.h ＞
class Complex
{ public:
Complex(double r =0, double v =0):real(r), virt(v) {}
friend Complex operator + (Complex a, Complex b);
friend ostream& operator ＜＜ ( ostream& out, Complex& a);
private:
double real;
double virt;
};
ostream& operator ＜＜ (ostream& out, Complex& a) { return out ＜＜ a.real ＜＜ " + " ＜＜ a.virt ＜＜ "i\n"; }
Complex operator + ( Complex a, Complex b)
{ return Complex( a.real + b.real, a.virt + b.virt) ; }
void main()
{ Complex a(2,5), b(7,8), c(0,0);
c=a+b;
cout ＜＜ c;
c=4.1 +a;
cout ＜＜ c;
c=b+5.6;
cout ＜＜ c;
}