#include <iostream>
#include <math.h>

using namespace std;

void CheckIfCodeValid( int size);
const short Size1 = 8;
const short Size2 = 13;
int ControlNumber = 0;
long S = 0;

int main()
{
    int Choice;


    while (1)
    {


        cout << "\n Menu" << endl;
        cout << "Wybierz rodzaj kodu kreskowego" << endl;
        cout << "\t1. EAN-8."
            << "\n\t2. EAN-13."
            << "\n\t9 By zakonczyc program"<<endl;
        cin >> Choice;
        switch (Choice)
        {
        case 1:
            CheckIfCodeValid(8);
            break;
        case 2:
            CheckIfCodeValid(13);
            break;
        case 9:
            exit(1);
        default:
            break;
        }
    }
}

void CheckIfCodeValid(int Size)
{
    char BarCodeAdd[18];
    int BarCode[18];
    cout << "\n Wprowadz swoj kod EAN" << endl;
    cin >> BarCodeAdd;

    for (int j = 0; j < Size; j++)
    {
        BarCode[j] = BarCodeAdd[j] - '0';
    }

    for (int i = 1; i < Size; i++)
    {
        S += ((2 - pow(-1, i)) * BarCode[i - 1]);
    }
    ControlNumber = 10 - (S % 10);
    cout << BarCode[Size - 1] << endl;
    cout << S << endl;
    cout << ControlNumber << endl;
    if (ControlNumber == BarCode[Size - 1])
    {
        cout << "\n Valid bar code";
        for (int i = 0; i < Size; i++)
        {
            cout << BarCode[i];
        }
    }
    else
    {
        cout << "\n Invalid bar code";
        cout << "\n Valid Barcode is: " << endl;
        BarCode[Size - 1] = ControlNumber;

        for (int i = 0; i < Size; i++)
        {
            cout << BarCode[i];
        }
    }
}