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I want to be able to call functions based on the data I read from file. So for each item type, I want to call the desired reader method. I wrote this code, but it does not compile where I want to add function pointers to the map. What is wrong?
#include <vector>
#include <map>
#include <iostream>
class reader
{
std::map< std::string, void(*)()> functionCallMap; // function pointer
void readA(){ std::cout << "reading A\n";};
void readB(){ std::cout << "reading B\n";};;
public:
reader()
{
*functionCallMap["A"] = &reader::readA;*
*functionCallMap["B"] = &reader::readB;*
}
void read()
{
auto (*f) = functionCallMap["A"];
(*f)();
}
};
I am filling the map at Constructor.
240
Function pointers can be stored in variables, structs, unions, and arrays and passed to and from functions just like any other pointer type. They can also be called: a variable of type function pointer can be used in place of a function name.
A function pointer is a pointer variable, but it holds the address of a function, not the address of a data item. The only things you can do with a function pointer are read its value, assign its value, or call the function that it points toward.
You can use std::function with a lambda or std::bind :
class reader
{
std::map<std::string, std::function<void()>> functionCallMap;
void readA() { std::cout << "reading A\n"; };
void readB() { std::cout << "reading B\n"; };
public:
reader()
{
functionCallMap["A"] = [this]() { readA(); };
functionCallMap["B"] = std::bind(&reader::readB, this);
}
void read()
{
functionCallMap["A"]();
functionCallMap["B"]();
}
};
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