[游戏开发]How to build a pointer array for member functions in class

An example illustrating the basic uses for member function pointer array

1. The results are as follows:

The value of x in instance example: 100
hello, world 100.

2. The corresponding codes for above results:

#include <iostream>
#include <stdio.h>

using namespace std;
class Example {
    public:
        Example(){
            this->x = 10;
        }
        ~Example(){}
        /*set the built-in functions in class with default return values to make the recall easy*/
        int print(int x) 
        { 
            printf("hello world %d.\n", this->x);
            return 0;
        }
        int set_x(int v)
        {
            this->x = v;
            return 0;
        }
        int get_x(int x) 
        {
            return this->x;
        }
    private:
        int x;
};

int main ()
{
    int (Example::*ptr[])(int)
    {
        &Example::print,
        &Example::set_x,
        &Example::get_x
    };
    Example example;
    (example.*ptr[1])(100);
    cout << "The value of x in instance example: " << (example.*ptr[2])(2) << endl;
    (example.*ptr[0])(1);
    return 0;
}

There are some notations I want to explain.

1. The argument in functions such as print and get_x are useless in the execution process. And its function is to make all the member functions have some prototype.
2. There are more ways to define the member function pointer array. But I just know this way.
3. Lastly, The intuition of above codes from this websites.