有以下程序 #include<iostream> using namespace std; class Base { private: char c; public: Base(char n):c(n){} ~Base() { cout<<c; } }; class Derived:public Base { private: char c; public: Derived(char n):Base(n+1),c(n){} ~Derived() { cout<<c; } }; int main() { Derived obj('x'); return 0; } 执行后的输出结果是