Creating a map of member functions example

func_member_ptrs.cpp

#include <iostream>
#include <map>
using namespace std;

class node{
public:
	node(int val){this->val = val; }
	int val;
};

class funcs{
public:
	funcs(char, node*, node*);
	int eval();
	int sub();
	int add();
	node* left;
	node* right;
	int val;
	char op;
	map<char, int (funcs::*)()> mapper;
};

funcs::funcs(char op, node* left, node* right){
	this->op = op;
	this->left = left;
	this->right = right;
	this->mapper['+'] = &funcs::add;
	this->mapper['-'] = &funcs::sub;
}

int funcs::eval(){
	return (this->*mapper[this->op])();
}

int funcs::add(){
	return this->left->val + this->right->val;
}

int funcs::sub(){
	return this->left->val - this->right->val;
}

int main(){
	node *a = new node(10);
	node *b = new node(20);
	funcs f('+', a, b);
	cout << f.eval() << endl;
	funcs f2('-', a, b);
	cout << f2.eval() << endl;
}