Basic Lambda Callback

#include <iostream>
#include <string>
#include <functional> 

class Button {
private:
    
    std::function<void()> onClick;

public:
    // TODO: Implement setCallback
    void setCallback(std::function<void()> cb) {
        onClick = cb;
    }

    // TODO: Implement press()
    void press() {
        if(onClick){
            onClick();
        }
    }
};

int main() {
    Button btn;

    btn.setCallback([](){std::cout << "Action Executed!" << std::endl;}); 	//directly passing the lambda function as a parameter

    int N;
    if (!(std::cin >> N)) return 0;

    for (int i = 0; i < N; ++i) {
        std::string cmd;
        std::cin >> cmd;

        if (cmd == "PRESS") {
            btn.press();
        }
    }
    return 0;
}

Solving Approach