c++ function pointers

cpp_fcnptr.cpp

#include <iostream>
#include <iomanip>
#include <string>
#include <array>
#include <algorithm>
#include <vector>

using namespace std;



int functionToCall(int x)
{
    return x;
}

int bar(int fcnptr)
{
    cout << "fcnptr returned " + to_string(fcnptr) << endl;
    return fcnptr;
}

// passing pointers
void printer(int *a)
{
    // an address of the pointer
    cout << &a << endl;
    // an address of what the pointer is pointing at
    cout << *a << endl;
    // the value that the pointer is pointing at
    cout << *a << endl;
}
 
int main()
{
    using validateFcn = int(int);

    validateFcn *fcnptr = functionToCall;
    cout << bar(fcnptr(1)) << endl;

    // passing pointers
    int i = 1;
    int *a;
    a = &i;
    printer(a);


    return 0;
}