#include <iostream>
#include <ctime>
#include <cstdlib>

void f_a(void)
{
    std::cout << "a";
}

void f_b(void)
{
    std::cout << "b";
}

void f_c(void)
{
    std::cout << "c";
}

void f_d(void)
{
    std::cout << "d";
}

void f_e(void)
{
    std::cout << "e";
}

void f_f(void)
{
    std::cout << "f";
}

class Printer
{
private:
    void (*pfnFunc)(void);
public:
    void setFunction(void (*pfnFunc)(void))
    {
        this->pfnFunc = pfnFunc;
    }

    void exec()
    {
        this->pfnFunc();
    }

    void (*getFunction(void))(void)
    {
        return this->pfnFunc;
    }

    static void (*getFunctionByID(int i))(void)
    {
        void (*functions[])(void) = { f_a, f_b, f_c, f_d, f_e, f_f };
        return functions[i];
    }
};

int main ( void )
{
    srand(time(NULL));

    Printer printer;

    for(int i = 0; i < 1000; i++) {
        printer.setFunction(Printer::getFunctionByID(rand() % 5));
        printer.exec();
    }

    std::cin.get();
}