Function Pointer และ Callback

#include <stdio.h>

int square(int value) { return value * value; }
int apply(int value, int (*operation)(int)) { return operation(value); }

int main(void) {
    printf("%d\n", apply(6, square));
    return 0;
}

#include <functional>
#include <iostream>

int apply(int value, const std::function<int(int)>& operation) {
    return operation(value);
}

int main() {
    int factor = 6;
    std::cout << apply(factor, [](int value) { return value * value; }) << '\n';
}