有以下程序
#include ＜iostream＞
using namespace std;
class Complex

public:
Complex(double r=0,double i=0):re(r),im(i)
double real() const return re;
double irnag() const return im;
Complex operator+(Complex c)const
( return Complex(re+c.re,im+c.im),
private:
double re,im;
;
int main()

Complex a=Complex(1,1)+Complex(5);
cout＜＜a.real()＜＜'+'＜＜a.imag()<<'i'＜＜endl;
return 0;

程序执行后的输出结果是( )。

A．6+6i
B．6+1i
C．1+6i
D．1+1i