Modern Recursive way

// BP_Self_Programs.cpp : Defines the entry point for the console application.
//

#include <iostream>
#include <string>
#include <conio.h>

#define s_c(wParam, lParam) ( static_cast<wParam> (lParam) )
#define r_c(wParam, lParam) ( reinterpret_cast<wParam &> (lParam) )

template <typename FROM, typename TO, typename STEP, typename SUM>
auto sum_recursive(FROM from, TO to, STEP step, SUM &sum) -> decltype(&sum) {
    if (from < to) {
        sum += from;
        from += step;

        return sum_recursive(from, to, step, sum);
    }

    return 0;
}


int main() {

    size_t choice;

    do {
        system("cls");

        std::cout << "Menu: \n";
        std::cout << "[1] Recursive sum in range with step & variable type choose\n";
        std::cout << "[2] Exit\n";

        std::cout << "Your choice: ";
        std::cin >> choice;

        switch (choice) {
            case 1:
                std::string var_type("");

                auto from(.0), to(.0), step(.0), sum(.0);

                std::cout << "Enter number to sum from: ";
                std::cin >> to;
                std::cout << "Enter number to sum to: ";
                std::cin >> to;
                std::cout << "Enter incrementation: ";
                std::cin >> step;

                std::cout << "Write variable type: \n";
                std::cin >> var_type;

                if (var_type == "float")
                    sum_recursive(s_c(float, from), s_c(float, to), s_c(float, step), r_c(float , sum));
                else if (var_type == "double")
                    sum_recursive(s_c(double, from), s_c(double, to), s_c(double, step), r_c(double, sum));
                else if (var_type == "int")
                    sum_recursive(s_c(int, from), s_c(int, to), s_c(int, step), r_c(int, sum));
                else if (var_type == "size_t")
                    sum_recursive(s_c(size_t, from), s_c(size_t, to), s_c(size_t, step), r_c(size_t,sum));
                else {
                    std::cout << "\n\nUnsupported type\n\n";
                    break;
                }

                std::cout << "\n\nSum: " << sum << std::endl << std::endl;
                _getch();
        }
    } while (choice != 2);

    return 0;
}