c++中的成员选择符

c++中支持仅能指向类成员的指针，对这种类型的指针进行数据的提取操作时，可使用如下两种类型的操作符：成员对象选择操作符.* 和 成员指针选择操作符->*

例一：

 #include <iostream>
 using namespace std;
 struct C
 {
     int x;
     float y;
     float z;
 };
 int main()
 {
     float f;
     int* i_ptr;

     C c1, c2;

     float C::*f_ptr; // a pointer to a float member of C
     f_ptr = &C::y;  //point to C member y
     c1.*f_ptr = 3.14; // set c1.y = 3.14
     c2.*f_ptr = 2.01; // set c2.y = 2.01

     f_ptr = &C::z;  // point to C member z
     c1.*f_ptr = -9999.99; //set c1.z = -9999.99

     f_ptr = &C::y; //point to C member y
     c1.*f_ptr = -777.77; // set c1.y

     f_ptr = &C::x; // ****Error: x is not float****

     f_ptr = &f; // ****Error: f is not a float member of C****

     i_ptr = &c1.x; //c1.x is an int

     //...

     return ;
 }

例二：定义和使用指向成员函数的指针

 #include <iostream>
 using namespace std;

 struct C
 {
     int x;
     short f(int){//....};
     short g(int){//....};
 };

 int main()
 {
     short s;
     C c;
     short (C::*meth_ptr) (int);
     meth_ptr = &C::f;

     s = (c.*meth_ptr)();
     C* ptr = &c;
     s = (ptr->*meth_ptr)();
     meth_ptr = &C::g;
     s = (c.*meth_ptr)();
     s = (ptr->*meth_ptr)();
     return ;
 }