已知類A有一個(gè)帶double型參數(shù)的構(gòu)造函數(shù),且將運(yùn)算符“+”重載為友元函數(shù),要是語句序列
A x(2.5),y(3.6),z(0);
Z=x+y;
能夠正常運(yùn)行,運(yùn)算符函數(shù)operator+應(yīng)在類中聲明為()。
A.friend A operator+(A,A);
B.friend A operator+(int,A &,);
C.friend A operator+(A,A &,);
D.friend A operator+(A &,A &);