PHP regular expressions in action: matching e-reader formats

In actual development, text format processing is often involved, and the format of the e-book reader is one of the factors that needs to be considered. In this article, we'll cover how to match e-reader formats using PHP regular expressions.

What is e-book reader format?

The e-book reader format is an e-book format that displays the content of the e-book through some special tags. Common e-book reader formats include EPUB and MOBI.

EPUB format is a widely used e-book format that uses XML-based markup to display the content of e-books. The MOBI format is an e-book format launched by Amazon. It also uses some special tags to display the content of e-books.

When performing regular expression matching, we need to consider the impact of these special tags on the text.

How to match the e-book reader format?

Below we will use some examples to introduce how to use PHP regular expressions to match e-book reader formats.

1. Match chapter titles in EPUB format

In EPUB format, chapter titles are generally contained between <h1> to <h6> tag. We can use the following regular expression to match chapter titles:

$pattern = "/<h[1-6]>(.+)</h[1-6]>/";

This regular expression uses <h[1-6]> and </h[ 1-6]> to match the beginning and end tags of the chapter title. Among them, [1-6] means matching numbers 1 to 6, (.) means matching any character (except newline character).

2. Match image tags in MOBI format

In MOBI format, pictures are generally included in <img> tags. We can use the following regular expression to match image tags:

$pattern = "/<img.*src="(.+?)".*>/";

This regular expression uses <img.*> to match the beginning of the image tag. Among them, .* means matching 0 or more arbitrary characters. Then use src=" to match the link address of the image, and use (. ?) to match any character in the image address. Finally, use .*> To match the end of the image tag.

Note that here we use ? to indicate non-greedy mode, which means that the matching process will try to match the shortest string to avoid too many matches characters.

3. Match footnote tags in EPUB and MOBI formats

In EPUB and MOBI formats, footnotes are generally included in <a> tag. We can use the following regular expression to match footnote tags:

$pattern = "/<a.*href="#(.+?)".*>(.*?)</a>/";

This regular expression uses to match the beginning of footnote tags. Among them, .* means matching 0 or more any characters. Then use href="# to match the link address of the footnote, and use (. ?) to Matches any characters in the link. Then use .*> to match the end of the link tag.

Finally use (.*?) to match the content of the footnote. Here we use non-greedy mode to avoid matching too many characters. In addition, we also use brackets to mark the content of the footnotes for subsequent extraction.

Summary:

This article introduces how to use PHP regular expressions to match e-book reader formats. Through the above examples, you should have learned how to use regular expressions to match text in different formats. When you encounter a situation where you need to match special text formats in actual development, you can refer to the regular expressions mentioned in this article to solve the problem.

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