Is there a way to check if an ISBN number is a valid number before storing into the database
I was wonder is a there a w开发者_高级运维eb service or a database out there that let us programmatically check if the user input is an valid ISBN number before storing it in the database. Or is there a algorithm that allow the programmer to do that
If look on the Wikipedia page, they have a simple algorithm to ensure than an ISBN is valid:
bool is_isbn_valid(char digits[10]) {
int i, a = 0, b = 0;
for (i = 0; i < 10; i++) {
a += digits[i]; // Assumed already converted from ASCII to 0..9
b += a;
}
return b % 11 == 0;
}
Of course, this doesn't ensure that it's real, only possible ;)
EDIT: This includes the ISBN 13 spec: (It's untested, and in the same pseudo-code as the wikipedia function)
bool is_valid_isbn(char isbn[]) {
int sum = 0;
if(isbn.length == 10) {
for(int i = 0; i < 10; i++) {
sum += i * isbn[i]; //asuming this is 0..9, not '0'..'9'
}
if(isbn[9] == sum % 11) return true;
} else if(isbn.length == 13) {
for(int i = 0; i < 12; i++) {
if(i % 2 == 0) {
sum += isbn[i]; //asuming this is 0..9, not '0'..'9'
} else {
sum += isbn[i] * 3;
}
}
if(isbn[12] == 10 - (sum % 10)) return true;
}
return false;
}
you might try:
http://isbndb.com/docs/api/
You could calc the checksum according to this algorithm: http://en.wikipedia.org/wiki/International_Standard_Book_Number#Check_digits. That doesn't tell you if there is actually a book with that number but it tells you if the number is correct.
Gory details here. So you can check the check digit and have a go at deducing what the country (and maybe publisher) are, but I don't see any way of checking there's a real book with that number
To validate just the checkdigit, and not compare against a known list of books, you could use the Apache Commons ISBNValidator class.
ISBNValidator validator = new ISBNValidator();
assertFalse(validator.isValid("12345678901234"));
assertTrue(validator.isValid("0-201-63385-X"));
Code example from: https://apache.googlesource.com/commons-validator/+/trunk/src/test/java/org/apache/commons/validator/ISBNValidatorTest.java
References: https://commons.apache.org/proper/commons-validator/apidocs/org/apache/commons/validator/routines/ISBNValidator.html
As others have suggested in my quick searches on SO try: idbndb
精彩评论