#include <iostream>
	#include <string>
	#include <map>
	
	// the functions we intend to map
	void disp1()
	{
	  std::cout<<"Disp1\n";
	}
	
	void disp2()
	{
	  std::cout<<"Disp2\n";
	}
	
	void disp3()
	{
	  std::cout<<"Disp3\n";
	}
	
	int main() {
		// create a new type, func_t, which describes a pointer
		// to a void function that takes no parameters (void).
		using func_t = void (*)(void);
		// declare a map from a string key to a func_t value,
		// and initialize it with a mapping of f1->disp1, f2->disp2
		// and f3->disp3
		std::map<std::string, func_t> functionMap = {
			{ "f1", disp1 }, { "f2", disp2 }, { "f3", disp3 }
		};
		
		// declare a string for reading input
		std::string input;
		
		// loop until there is no more input on std::cin.
		while (std::cin.good()) {
			// prompt
			std::cout << "Which disp (f1, f2, f3)? ";
			// fetch the next line of text from cin, without the \n
			std::getline(std::cin, input);
			// if the input is empty we ran out of input or the user
			// input a blank line. either way, stop.
			if (input.empty())
				break;
				
			std::cout << "You chose " << input << "\n";
			
			// look for the key in the map. if the key is not found,
			// it will equal the special iterator functionMap.end()
			auto it = functionMap.find(input);
			// If it's not functionMap.end then we have a valid iterator.
			// it->first is the key, it->second is the function pointer.
			if (it != functionMap.end()) {
				// to use a function pointer, just add the () with any
				// arguments after the variable name.
				// remember, it->second is the function pointer.
				it->second();
			} else {
				std::cout << "Invalid entry.\n";
			}
		}
	}