C++ How do you create a map that takes in a string and returns a func

Question

I was wondering if there was a way that I could make a map(in C++) return a func. This is my code now and it doesn't work, I get a compiler error.

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

map<string, void()> commands;

void method()
{
    cout << "IT WORKED!";
}

void Program::Run()
{
    commands["a"]();
}

Program::Program()
{
    commands["a"] = method;
    Run();
}

Any bit of advice would be awesome! Thank you in advance.

With C++11, std::map<std::string, std::function<void()>>

Qaz
– Qaz

2012-10-23 03:01:33 +00:00
Commented Oct 23, 2012 at 3:01 — Qaz
– Qaz, Commented Oct 23, 2012 at 3:01

Jerry Coffin · Accepted Answer · 2012-10-23 03:07:56Z

4

You can't store a function in a map -- only a pointer to a function. With a few other minor details cleaned up, you get something like this:

#include <map>
#include <iostream>
#include <string>

std::map<std::string, void(*)()> commands;

void method() {
    std::cout << "IT WORKED!";
}

void Run() {
    commands["a"]();
}

int main(){ 
    commands["a"] = method;
    Run();
}

At least with g++ 4.7.1, this prints IT WORKED!, as you apparently wanted/expected.

answered Oct 23, 2012 at 3:07

Jerry Coffin

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SwiftMango · Accepted Answer · 2012-10-23 03:10:31Z

2

Again typedef is your friend.

typedef void (*func)();
map<string, func> commands;

answered Oct 23, 2012 at 3:10

SwiftMango

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