// @topic T061110 std::set demo, range-based for loop
// @brief unique integer entry

// problem to solve:
// have a user enter integers,
// but no duplicate values should be accepted

#include <iostream>
#include <cstdlib>
#include <set>
int main()
{
    std::set< int > int_set;
    for (;;) {
        int value;
        std::cout << "\nEnter an integer or 0 to exit: ";
        std::cin >> value;
        if (value == 0) break;
        if ( int_set.count( value ) ) {
            std::cout << "It's a duplicate!\n";
        } else {
            std::cout << "Okay!\n";
            int_set.insert(value);
        }
    }//for

    std::cout << "The values you've entered are:\n";
    for ( int value : int_set ) {
        std::cout << value << " ";
    }

    std::cout << "\n";
    system("pause");
    return 0;
}