2_5_ISBN_validator.cpp

#include <iostream>

using std::cin;
using std::cout;

/*
ISBN validator without using arrays.
*/

/* (AD): Define a new type for enum (T_ISBNPART_ENUM) and name enums as T_ISBNPART_PREFIX, T_ISBNPART_GROUP... */
enum isbnPart {PREFIX, GROUP, REGISTRANT, PUBLICATION, CHECK, COMPLETED};

bool verifyPart(int nr, int digitCount, int part);
bool verifyCheckDigit(int nr);

int main()
{
    char digitChar;
    char ch = '0';
    int nr = 0;
    int digit = 0;
    int modulo = 0;
    int part = PREFIX;
    int digitCount = 0;
    int totalDigitCount = 0;
    int checkSum = 0;
    int pos = 1;
    bool invalidNr = false;


    cout << "Type in ISBN number. 13 digits to validate, 12 digits to get the checksum digit:\n";


    do {
        ch = cin.get();
        digitCount++;
        if(ch == '-' || ch == 10)
            {
            if (!verifyPart(nr, digitCount, part))
            {
                invalidNr = true;
                break;
            }
            part = ++part % 6;
            digitCount = nr = 0;
        } else {
            nr = nr*10 + (ch - '0');
            digit = ch - '0';
            totalDigitCount++;
            checkSum += (pos % 2 == 0) ? digit * 3: digit;
            pos++;
        }
    } while(ch != 10);


    // Check if the number is too long
    if (!(part == CHECK && totalDigitCount==12) && !(part == COMPLETED && totalDigitCount==13))
    {
        invalidNr = true;
    }

    // Check if the number is valid in its format
    if (invalidNr || part < CHECK || part > COMPLETED)
    {
        cout << "The number is not valid!\n";
    } // Then get the checksum digit
    else if (part == CHECK)
    {
        int checkDigit = 10 - checkSum % 10;
        cout << "The check digit is " << checkDigit << " \n";
    } // Else check the checksum
    else if (part == COMPLETED)
    {
        if (checkSum % 10 == 0)
        {
            cout << "The ISBN is valid\n";
        } else {
            cout << "The ISBN is not valid\n";
        }
    }
    else
    {
        cout << "Something went wrong!\n";
    }
    cin.get();
    return 0;
}


bool verifyPart(int nr, int digitCount, int part)
{
    bool isVerified = false;
    switch(part)
    {
        case PREFIX:
            isVerified = (nr == 978 || nr == 979);
            break;
        case GROUP:
            isVerified = (digitCount >= 1 && digitCount <= 5);
            break;
        case REGISTRANT:
            isVerified = (digitCount >= 1 && digitCount <= 6);
            break;
        case PUBLICATION:
            isVerified = (digitCount >= 1 && digitCount <= 7);
            break;
        case CHECK:
            isVerified = (nr < 10 || nr >= 0);
            break;
        case COMPLETED:
            isVerified = false;
            break;
        default:
            isVerified = false;
    }
    return isVerified;

}