fact.cxx

#include <iostream>
#include <functional>

using namespace std;

int main(int argc, char **argv){

    function<int(int)> factorial = [&factorial](int val) -> int {
        if( val <= 1 ) {
            return 1;
        }
        else {
            return val * factorial(val-1);
        }
    }; //Note: Must be in a function body or else warnings appear.

    cout << factorial(12);
    cout << endl;

    return 0;
}