#include <cstdio>
#include <cmath>
#include <cstdlib>

using namespace std;

//#define CLEAR_STDIN do {} while ( (c = getchar()) != '\n' && c != EOF )

double _sum(double x, double y) { return x + y;}
double _sub(double x, double y) { return x - y;}
double _mul(double x, double y) { return x * y;}
double _div(double x, double y) { return x / y;}
double _rem(double x, double y) { return (long)x % (long)y;} //accuracy loss!


struct
{
    const char *description;
    char symbol;
    double (*function)(double, double);
} ops[] = {{"sum", '+', _sum}   ,{"sub", '-', _sub}
      ,{"mul", '*', _mul}   ,{"div", '/', _div}
      ,{"rem", '%', _rem}   ,{"pow", '^', pow}
};


int main ()
{
    int i, c;
    cout << "****\n";
    for (i = 0; i < sizeof ops/sizeof ops[0]; i++){
        cout << i + 1 << "- " << ops[i].description << " ( " << ops[i].symbol<<")";

        if (i % 2)  cout << "\n";
        else        cout << "\t\t\t\t\t";
    }

    unsigned choice;
    double x,y;
    cout << "\n****\nSelect:  ";
    cin >> choice; choice--;
    //CLEAR_STDIN;
    if (choice > i){
        cout << "Invalid; exiting.";
        return 1;
    }
    // function with 2 parameters
    cout << "Enter Number 1: ";
    cin >> x;
    cout << "Enter Number 2: ";
    cin >> y;
    cout << x << ops[choice].symbol <<  y << " = " << ops[choice].function(x,y);

}