#include <iostream>
// Ivan Novick
// May 20, 2009
// C++ code to detect and ignore bad input from cin

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

    int number;

    while(1) {

        std::cout << "Enter a number and I will multiply it by 2: ";
        std::cin >> number;

        // here is an example of how to detect bad input when expecting
        // a number and getting a char or some other input
        if (!std::cin){
            std::cin.clear();
            while(std::cin.get()!='\n'){
                continue;
            }
            std::cout << "bad input detected" << std::endl;
            continue;
        }

        if (!number){
            break; // no more input
        }
        std::cout << "The result is: " << number * 2 << std::endl;
    }

    return 0;
}