ISBN Help

Question

Se7Olutionyg -7 Junior Poster

17 Years Ago

// CS 210 EDDIE CHEN
// THIS IS PROGRAM 4 (ISBN-Check), a program that verifies ISBN.

#include <iostream>
#include <fstream>                                                                            // REQUIRED FOR FILE STREAMS
#include <cstdlib>                                                                            // FOR DEFINITION OF EXIT_FAILURE
#include <cctype>
#include <string>
using namespace std;

// ASSOCIATE STREAMS WITH EXTERNAL FILE NAMES
#define inFile "isbntest.txt"                                                                // LINKED ISBN FILE (LIST) SOURCE

// FUNCTIONS USED
void menuPrompt ();                                                                            // MAIN MENU USER INSTRUCTION
void userVal ();                                                                            // MANUAL INPUT VALIDATION
int readFile ();                                                                            // LINKED FILE VALIDATION
bool isbnCheckForUser (string isbn);                                                        // ISBN VALIDATION FUNCTION FOR USER INPUT
bool isbnCheckForFile (string isbn);                                                        // ISBN VALIDATION FUNCTION FOR FILE INPUT

int main ()
{
    char choice;                                                                        // INPUT-MAIN MENU CHOICE
    string isbn;

        do
        {
            menuPrompt ();
            cin >> choice;
            switch (choice)
            {
            case '1':
                    userVal ();
                    break;
            case '2':
                    readFile ();
                    break;
            case '3':
                    cout << "Thank you for using ISBN-Check. Have a nice day!" << endl;
                    break;
            default:
                    cerr << "Oops! Incorrect selection. Please try again." << endl;
            }            
        }
        while (choice != '3');
    
    system ("pause");

    return 0;
}

void menuPrompt ()
{
    cout << "Welcome to ISBN-Check." << endl;
    cout << "This program will verify the format of your ISBN(s)." << endl;
    cout << "To manually input the ISBN(s), enter 1." << endl;
    cout << "To verify the ISBN(s) from the linked .txt file, etner 2." << endl;
    cout << "When you're done, enter 3 to exit the program." << endl;
}

void userVal ()
{
    char subchoice;                                                                            // INPUT- SUB MENU CHOICE
    string isbn;                                                                            // INPUT- ISBN STRING
    do
    {
    cout << "Enter an ISBN:";
    cin >> isbn;
    isbnCheckForUser (isbn);
    if (isbnCheckForUser (isbn) == true)
        cout << "This is a valid ISBN." << endl;
    else
        cout << "This is NOT a valid ISBN." << endl;
    cout << endl;
    cout << "To go back to the main menu, enter 1." << endl;
    cout << "To continue manually inputting ISBN(s), enter any digit besides 1." << endl;
    cin >> subchoice;
    }
    while (subchoice != '1');
    
}

int readFile ()
{
    ifstream fin;
    string isbn;
    fin.open (inFile);
    if (fin.fail ())
    {
        cerr << " ERROR: Cannot open " << inFile << " for input. " << endl;
        return EXIT_FAILURE;                                                                // FAILURE RETURN
    }
    fin >> isbn;
    isbnCheckForFile (isbn);
    if (isbnCheckForFile (isbn) == true)
        cout << "This is a valid ISBN." << endl;
    else
        cout << "This is NOT a valid ISBN." << endl;
        
}

bool isbnCheckForUser (string isbn)
{
    int isbn0;
    int isbn1;
    int isbn2;
    int isbn3;
    int isbn4;
    int isbn5;
    int isbn6;
    int isbn7;
    int isbn8;
    int isbn9;
    int sum;
    int modulo;
    
    if (isbn.at(0) == '-' || isbn.at(isbn.length()-1) == '-')
        cout << "This is NOT a valid ISBN." << endl;
        
        isbn.find('-');                                
        isbn.erase('-');
        isbn.at(0) = isbn0;
        isbn.at(1) = isbn1;
        isbn.at(2) = isbn2;
        isbn.at(3) = isbn3;
        isbn.at(4) = isbn4;
        isbn.at(5) = isbn5;
        isbn.at(6) = isbn6;
        isbn.at(7) = isbn7;
        isbn.at(8) = isbn8;
        isbn.at(9) = isbn9;
            
    if (isbn.at(isbn.length()-1) == 'x' || isbn.at(isbn.length()-1) == 'X')
        isbn9 = 10;
        
    sum= isbn0 * 1 + isbn1 * 2 + isbn2 * 3 + isbn3 * 4 + isbn4 * 5 + isbn5 * 6 + isbn6 * 7 + isbn7 * 8 + isbn8 * 9;
    modulo = sum / 11;
    
    if (modulo = 10 && isbn.at(isbn.length()-1) == 'x' || isbn.at(isbn.length()-1) == 'X')
        cout << "This is a valid ISBN." << endl;
    
    else if (modulo = 10 && isbn.at(isbn.length()-1) != 'x' || isbn.at(isbn.length()-1) != 'X')
        cout << "This is NOT a valid ISBN." << endl;
            
    else if (modulo != isbn9)
        cout << "This is Not a valid ISBN." << endl;
            
    else
        cout << "This is a valid ISBN." << endl;
}

bool isbnCheckForFile (string isbn)
{
    ifstream fin;
    int num_of_isbn;
    int count;
    int isbn0;
    int isbn1;
    int isbn2;
    int isbn3;
    int isbn4;
    int isbn5;
    int isbn6;
    int isbn7;
    int isbn8;
    int isbn9;
    int sum;
    int modulo;

    getline(istream& fin, string& num_of_isbn, char '\n');
    fin.ignore( 80, '\n');
    while (!fin.eof())
        {
            for (count=0; count < num_of_isbn; count++)
                {
                    getline (fin, isbn);
                    if (isbn.at(0) == '-' || isbn.at(isbn.length()-1) == '-')
                    cout << "This is NOT a valid ISBN." << endl;
                    isbn.find('-');                                //HOW DO I COUNT THE NUMBER OF DASHES?
                    isbn.erase('-');
                    isbn.at(0) = isbn0;
                    isbn.at(1) = isbn1;
                    isbn.at(2) = isbn2;
                    isbn.at(3) = isbn3;
                    isbn.at(4) = isbn4;
                    isbn.at(5) = isbn5;
                    isbn.at(6) = isbn6;
                    isbn.at(7) = isbn7;
                    isbn.at(8) = isbn8;
                    isbn.at(9) = isbn9;
                    if (isbn.at(isbn.length()-1) == 'x' || isbn.at(isbn.length()-1) == 'X')
                    isbn9 = 10;
                    sum= isbn0 * 1 + isbn1 * 2 + isbn2 * 3 + isbn3 * 4 + isbn4 * 5 + isbn5 * 6 + isbn6 * 7 + isbn7 * 8 + isbn8 * 9;
                    modulo = sum / 11;
                    if (modulo = 10 && isbn.at(isbn.length()-1) == 'x' || isbn.at(isbn.length()-1) == 'X')
                    cout << "This is a valid ISBN." << endl;
                    else if (modulo = 10 && isbn.at(isbn.length()-1) != 'x' || isbn.at(isbn.length()-1) != 'X')
                    cout << "This is NOT a valid ISBN." << endl;
                    else if (modulo != isbn9)
                    cout << "This is Not a valid ISBN." << endl;
                    else
                    cout << "This is a valid ISBN." << endl;
                }
        }
}

I have the problem with getline in line 170. Please help me

c++ open-source

3 Contributors
8 Replies
196 Views
2 Days Discussion Span
Latest Post 17 Years Ago Latest Post by Ancient Dragon

Dani AI

Generated 6 Months Ago

Short summary and immediate fixes (why getline at line 170 fails)

The getline line in your code looks like a declaration instead of a call and the input stream is being used before it is verified-open. As pointed out, make sure the ifstream is opened successfully before reading and call getline correctly.
There are also several logic and type errors in the ISBN routine that will either crash (out-of-range accesses) or always produce the wrong result: assigning characters to ints backwards, using division instead of remainder, using = instead of ==, and using the wrong weight scheme for ISBN-10.

Practical, minimal changes to get a correct, robust ISBN-10 check

Open the file and check the stream before reading.
Strip hyphens/whitespace from the input string and verify you have exactly 10 characters.
Convert characters to numeric values (last char may be X meaning 10).
Use weights 10..1 and test (sum % 11) == 0 for validity.
Always check string length before using at() or operator[] to avoid exceptions.

Example validator and read loop (adapt and drop into your program)

#include <fstream>
#include <iostream>
#include <string>
#include <cctype>
#include <algorithm>

bool isValidISBN10(const std::string &raw) {
    std::string s;
    for (char c : raw) if (!std::isspace((unsigned char)c) && c != '-') s.push_back(c);
    if (s.size() != 10) return false;
    int sum = 0;
    for (int i = 0; i < 10; ++i) {
        int v;
        if (i == 9 && (s[i]=='X' || s[i]=='x')) v = 10;
        else if (std::isdigit((unsigned char)s[i])) v = s[i] - '0';
        else return false;
        sum += (10 - i) * v;
    }
    return (sum % 11) == 0;
}

void processFile(const std::string &path) {
    std::ifstream in(path);
    if (!in) { std::cerr << "Cannot open file\n"; return; }
    std::string line;
    while (std::getline(in, line)) {
        if (line.empty()) continue;
        std::cout << (isValidISBN10(line) ? "This is a valid ISBN." : "This is NOT a valid ISBN.") << '\n';
    }
}

Notes and troubleshooting

If your input file starts with a count, read that count with the extraction operator into an int, then use getline for the following lines.
Follow ’s direction to use indexing/arrays (or the string indexing above) rather than many separate variables like isbn0..isbn9.
Fix operator mistakes (== vs =) and use % for modulus. These changes address the runtime crash and correctness issues while keeping your program structure.

All 8 Replies

Ancient Dragon 5,243 Achieved Level 70

17 Years Ago

>> getline(istream& fin, string& num_of_isbn, char '\n');
That is a function prototype, not a function call. As written, it will do nothing. If you want to actually call getline() then you need to change it to this: getline(fin, num_of_isgn); -- Not the '\n' parameter (last parameter) is not needed because that is the default.

Prabakar 77 Posting Whiz

17 Years Ago

>>isbn1, isbn2, ...
why not use isbn[10]?
And what are the contents of the infile?

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Se7Olutionyg -7 Junior Poster · Answer 1 · 2008-11-01T11:19:24+00:00

Se7Olutionyg -7 Junior Poster

17 Years Ago

I changed it ,but it still not run though, thank you

Se7Olutionyg -7 Junior Poster · Answer 2 · 2008-11-02T09:16:50+00:00

Se7Olutionyg -7 Junior Poster

17 Years Ago

I haven't learn the array yet, that's why...

Se7Olutionyg -7 Junior Poster · Answer 3 · 2008-11-03T04:35:44+00:00

Se7Olutionyg -7 Junior Poster

17 Years Ago

help please

Ancient Dragon 5,243 Achieved Level 70 Team Colleague Featured Poster · Answer 4 · 2008-11-03T04:58:16+00:00

The ifstream fin was never opened. You have to call fin.open("<the filename here>"); before line 170

Se7Olutionyg -7 Junior Poster · Answer 5 · 2008-11-03T07:00:40+00:00

Se7Olutionyg -7 Junior Poster

17 Years Ago

fin.open(inFile);
is this what you mean???

Ancient Dragon 5,243 Achieved Level 70 Team Colleague Featured Poster · Answer 6 · 2008-11-03T09:01:08+00:00

fin.open(inFile);
is this what you mean???

Maybe -- depends on what inFile is defined to be. If it's a std::string object then fin.open(inFile.c_str());

ISBN Help

Dani AI

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