单项选择题

有如下程序: #include #include using namespace std; class MyString{ public; char str[80]; MyString(const char*s) {strcpy(str,s);} MyString&operator+=(MyString a){ strcat(str,a.str); return*this; } }; ostream&operator<<(ostream&s,const MyString&z){return s << z.str} int main(){ MyString x("abc"),y("cde"); cout<<(x+=y)<
A.abc
B.cde
C.abcde
D.abccde