正则表达式区分ISBN

本文介绍了正则表达式区分ISBN-10和ISBN-13的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我有一条If-else语句，该语句检查字符串以查看是否有ISBN-10或ISBN-13(书ID).

I have an If-else statement which checks a string to see whether there is an ISBN-10 or ISBN-13 (book ID).

我面临的问题是在ISBN-13检查之前发生的ISBN-10检查，ISBN-10检查将与10个字符或更多字符匹配，因此可能将ISBN-13误认为是ISBN-10

The problem I am facing is with the ISBN-10 check which occurs before the ISBN-13 check, the ISBN-10 check will match anything with 10 characters or more and so may mistake an ISBN-13 for an ISBN-10.

这是代码...

$str = "ISBN:9780113411436"; if(preg_match("/\d{9}(?:\d|X)/", $str, $matches)){ echo "ISBN-10 FOUND\n"; //isbn returned will be 9780113411 return 0; } else if(preg_match("/\d{12}(?:\d|X)/", $str, $matches)){ echo "ISBN-13 FOUND\n"; //isbn returned will be 9780113411436 return 1; }

如何确保避免出现此问题?

How do I make sure I avoid this problem?

推荐答案

为此，您实际上只需要一个正则表达式.然后，执行更有效的strlen()检查以查看匹配的项.以下内容将匹配带或不带连字符的字符串中的ISBN-10和ISBN-13值，并可选地以字符串ISBN:，ISBN:(space)或ISBN(space)开头.

You really only need one regex for this. Then do a more efficient strlen() check to see which one was matched. The following will match ISBN-10 and ISBN-13 values within a string with or without hyphens, and optionally preceded by the string ISBN:, ISBN:(space) or ISBN(space).

function findIsbn($str) { $regex = '/\b(?:ISBN(?:: ?| ))?((?:97[89])?\d{9}[\dx])\b/i'; if (preg_match($regex, str_replace('-', '', $str), $matches)) { return (10 === strlen($matches[1])) ? 1 // ISBN-10 : 2; // ISBN-13 } return false; // No valid ISBN found } var_dump(findIsbn('ISBN:0-306-40615-2')); // return 1 var_dump(findIsbn('0-306-40615-2')); // return 1 var_dump(findIsbn('ISBN:0306406152')); // return 1 var_dump(findIsbn('0306406152')); // return 1 var_dump(findIsbn('ISBN:979-1-090-63607-1')); // return 2 var_dump(findIsbn('979-1-090-63607-1')); // return 2 var_dump(findIsbn('ISBN:9791090636071')); // return 2 var_dump(findIsbn('9791090636071')); // return 2 var_dump(findIsbn('ISBN:97811')); // return false

这将搜索提供的字符串，以查看它是否包含可能的ISBN-10值(返回1)或ISBN-13值(返回2).如果没有，它将返回false.

This will search a provided string to see if it contains a possible ISBN-10 value (returns 1) or an ISBN-13 value (returns 2). If it does not it will return false.

请参见上文的 演示 .

See DEMO of above.

对于 strict 验证，针对ISBN的Wikipedia 文章具有针对的一些PHP验证功能href ="en.wikipedia/wiki/International_Standard_Book_Number#Alternative_calculation"> ISBN-10 和 ISBN-13 .下面是这些示例的复制，整理和修改，以用于上述功能的稍作修改的版本.

For strict validation the Wikipedia article for ISBN has some PHP validation functions for ISBN-10 and ISBN-13. Below are those examples copied, tidied up and modified to be used against a slightly modified version of the above function.

将返回块更改为此:

return (10 === strlen($matches[1])) ? isValidIsbn10($matches[1]) // ISBN-10 : isValidIsbn13($matches[1]); // ISBN-13

验证ISBN-10:

function isValidIsbn10($isbn) { $check = 0; for ($i = 0; $i < 10; $i++) { if ('x' === strtolower($isbn[$i])) { $check += 10 * (10 - $i); } elseif (is_numeric($isbn[$i])) { $check += (int)$isbn[$i] * (10 - $i); } else { return false; } } return (0 === ($check % 11)) ? 1 : false; }

验证ISBN-13:

function isValidIsbn13($isbn) { $check = 0; for ($i = 0; $i < 13; $i += 2) { $check += (int)$isbn[$i]; } for ($i = 1; $i < 12; $i += 2) { $check += 3 * $isbn[$i]; } return (0 === ($check % 10)) ? 2 : false; }

请参见上文的 演示 .

See DEMO of above.