有如下程序:#include#includeusing 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