PHP function code for verifying ISBN code_PHP tutorial

For detailed information, please refer to: International Standard Book Number – Wikipedia. Here is a brief description of what an ISBN code is:
International Standard Book Number (ISBN; intended to be pronounced is-ben), is an internationally accepted book or independent Code for publications (other than regularly published journals). Publishers can clearly identify all non-journal books by their International Standard Book Numbers. An ISBN has only one or one corresponding publication corresponding to it. If the new version does not have major changes in content based on the original old version, it will not receive a new ISBN number when it is published. When the paperback version is changed to hardcover publication, the original corresponding ISBN number should also be withdrawn.
We usually see two types of ISBN codes: 10-digit and 13-digit. The 10-digit ISBN has been discontinued since January 2007. Currently, the ISBN codes of newly published books are all 13-digit. Considering that a rigorous library management program must take into account many aspects, because there are still a huge number of books with 10-digit ISBN codes in existence, so to verify the correctness of book ISBN codes, you must consider both 10-digit and 13-digit ISBN codes. bit situation. From Wikipedia, we can learn that the last digit of the ISBN code is the check code. In fact, if you want to verify the accuracy of the ISBN code, you need to calculate the check code of the ISBN to see if it matches the last digit. The verification mentioned here only verifies whether the ISBN is legal in composition, but does not verify whether it is the ISBN of a published book. The following is the ISBN code verification algorithm provided by Wikipedia:
Calculation method of check code (10 digits)
Assume that the first 9 digits of an International Standard Book Number are: 7-309-04547
Calculate the weighted sum S: S = 7×10+3×9+0×8+9×7+0×6+4×5+5×4+4×3+7×2 = 226
Calculate the remainder M of S÷11: M = 226 mod 11 = 6
Calculate the difference N of 11 – M: N = 11 ? 6 = 5
If N = 10, the check code is the letter "X"
If N = 11, the check code is the number "0"
If N is another number, the check code is the number N
So, the check code of this book is 5; if the ISBN code provided by the user is 7-309-04547-6, then the check fails
Calculation method of check digit (13 digits)
Suppose the first 12 digits of an ISBN number are: 978-986-181-728
Calculate the weighted sum S: S = (9× 1)+(7×3)+(8×1)+(9×3)+(8×1)+(6×3)+(1×1)+(8×3)+(1×1) +(7×3)+(2×1)+(8×3) = 164
Calculate the remainder M of S÷10: M = 164 mod 10 = 4
Calculate the difference N of 10 – M: N = 10 ? 4 = 6
If N = 10, the check code is the number "0"
If N is another number, the check code is the number N
So, the check code of this book is 6 . The complete International Standard Book Number is ISBN 978-986-181-728-6
Okay, that’s it for the background knowledge. Below is the ISBN code verification function (php version) I wrote. You can use it directly if needed:

Copy code The code is as follows:

function isbn_sum($isbn, $len)
{
/*
* This function is used to calculate the ISBN weighted sum
* Parameter description:
* $isbn: isbn code
* $len: isbn code length
*/
$sum = 0;
if ($len == 10)
{
for ($i = 0; $i < $len-1; $i++)
{
$sum = $sum + (int)$isbn[$i] * ($len - $i);
}
}
elseif ($len == 13)
{
for ($i = 0 ; $i < $len-1; $i++)
{
if ($i % 2 == 0)
$sum = $sum + (int)$isbn[$i];
else
$sum = $sum + (int)$isbn[$i] * 3;
}
}
return $sum;
}
function isbn_compute($ isbn, $len)
{
/*
* This function is used to calculate the ISBN last digit check code
* Parameter description:
* $isbn : isbn code
* $ len : isbn code length
*/
if ($len == 10)
{
$digit = 11 - isbn_sum($isbn, $len) % 11;
if ($ digit == 10)
$rc = 'X';
else if ($digit == 11)
$rc = '0';
else
$rc = (string) $digit;
}
else if($len == 13)
{
$digit = 10 - isbn_sum($isbn, $len) % 10;
if ($digit = = 10)
$rc = '0';
else
$rc = (string)$digit;
}
return $rc;
}
function is_isbn( $isbn)
{
/*
* This function is used to determine whether it is an ISBN number
* Parameter description:
* $isbn : isbn code
*/
$ len = strlen($isbn);
if ($len!=10 && $len!=13)
return 0;
$rc = isbn_compute($isbn, $len);
if ($isbn[$len-1] != $rc) /* The ISBN mantissa does not match the calculated check code*/
return 0;
else
return 1;
}

After the function is written, it can be called directly. The following is a calling example:

Copy the code The code is as follows:

In addition, I wrote an online ISBN verification tool. You can use this tool to verify the legitimacy of the ISBN code online. You can click the following link to use it: ISBN Code Online Verification Tool

http://www.bkjia.com/PHPjc/322828.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/322828.htmlTechArticleFor detailed information, please refer to: International Standard Book Number – Wikipedia. Here is a brief description of what an ISBN code is: International Standard Book number (International Standard Book Number, ISBN; intended to be pronounced...