Detailed explanation of the function to verify ISBN code in PHP

Detailed explanation of the function to verify ISBN code in PHP_PHP tutorial

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Release： 2016-07-20 11:10:58

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This article will talk about the ISBN verification method. Students in need can refer to it. 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.

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 11 – The difference N of 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, and the check code is the number N
Therefore, the check code of this book is 5; if the ISBN code provided by the user is 7-309-04547-6, then the verification 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
Therefore, 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. If necessary, you can directly Use

and the code is as follows

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/**
* Name: PHP function to verify ISBN code
* Author: Pandan
* Last modified: September 26, 2010
*/

* This function is used for calculation 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;

$rc = '0'; 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 Calling example:

The code is as follows

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