cppBinToDec

#include <iostream>

// 101011
// 101210

int main()
{
    int bin{ 21111111 };
    int dec{ 0 };
    int bit{ 0 };
    bool good{ true };
    std::cout << "Enter binary number\n";
    std::cin >> bin;

    //    for (int mul{ 1 }, bit{ 0 }; (bit = bin % 10), bin and ((bit == 0 or bit == 1) ? 1 : (dec = 0, good = false)); dec += bit * mul, mul *= 2, bin /= 10);
    for (int mul{ 1 }; bin; mul *= 2, bin /= 10)
    {
        bit = bin % 10;

        if (bit == 0 or bit == 1)
        {
            dec += bit * mul;
        }
        else
        {
            dec = 0;
            good = false;
            break;
        }
    }

    if (good)
    {
        std::cout << "Number in dec is " << dec << '\n';
    }
    else
    {
        std::cout << "Error in bin nubber!\n";
    }

    return 0;
}