1. 普通成员函数指针
    2. //define and initialize
    3. void (A::*p)(void) = &A::func;
    4. //caller
    5. A *a = new A();
    6. //call, parentheses are needed
    7. (a->*p)();
    9. 静态成员函数指针
    10. A a;
    11. void (*p)() = &A::funb;
    12. p();