function pointers (exercise)

fpe.cpp

#include <iostream>

/// function pointers
double sample_func (double d1, double d2)
{
    std::cout << __func__ << " was called ";
}

int add (int n1, int n2)
{
    std::cout << __func__ << " is called that has int parameter" << std::endl;
    return n1 + n2;
}

double add (double d1, double d2)
{
    std::cout << __func__ << " is called that has double parameter" << std::endl;
    return d1 + d2;
}

int (*ptr_add)(int, int) = add; /// or ptr_add = add || ptr_add = &add;

/// function overload pointers

double (*pof)(double, double) = add; /// needs to be exact so pof is a pointer to a function that have parameters of two double and returns int which is int add (double d1, double d2)

/// function pointer parameters

double f1_mimic(double d1, double d2, double (*m)(double, double))
{
    return m(d1, d2);
}


/// function pointer parameters with type alias typedef

typedef int (*tf)(int, int); /// equivalent to typedef int tf(int, int);

int f2_mimic(int i1, int i2, tf f)
{
    return f(i1, i2);
}

/// function pointer parameters with decltype and typedef

typedef decltype(sample_func) d_ptr; /// equivalent to typedef decltype(sample_func) *d_ptr;

double f3_mimic (double d1, double d2, d_ptr dp)
{
    return dp(d1, d2);
}

int main()
{
    std::cout << add(2, 2) << std::endl
              << ptr_add(4, 4) << std::endl
              << (*ptr_add)(10, 10) << std::endl;

    std::cout << pof (2.3, 2.4) << std::endl
              << add (2.3, 2.65) << std::endl;

    std::cout << f1_mimic(2.3, 2.4, add);

    std::cout << f2_mimic(200, 200, add);

    std::cout << f3_mimic(420, 420, add);

    return 0;
}