Regular replacement of html tags

HTML is the standard language for web pages, but in some cases, we need to extract plain text from HTML web pages. In this case, replacing HTML tags is useful. This article will introduce how to use regular expressions to replace HTML tags.

First of all, what is a regular expression?

Regular expression is an expression used to match strings. It can be used to search, replace and extract text. Regular expressions are commonly used in text processing, such as searching and finding text in programming or text editors.

Replace HTML tags using regular expressions

In many cases, we want to remove HTML tags so that we can extract text from a web page. Let's see how to remove HTML tags using regular expressions.

In PHP, we can use the preg_replace() function to replace HTML tags. Here is some sample code:

$html = "<h1 id="Hello-world">Hello, world!</h1><p>This is a paragraph!</p>";
$stripped_html = preg_replace('/<[^>]*>/', '', $html);
echo $stripped_html;

The output is:

Hello, world!This is a paragraph!

In this example, we define a $html variable and set it to a string containing HTML tags. We then use the preg_replace() function, which uses a regular expression to replace all HTML tags. The regular expression '/1*>/' matches all characters starting with "". These matching characters are then replaced with the '' empty string.

Another example:

$html = "<p>This is a <strong>paragraph</strong> with <a href='https://example.com'>a link</a>.</p>";
$stripped_html = preg_replace('/<[^>]*>/', '', $html);
echo $stripped_html;

The output is:

This is a paragraph with a link.

In this example, the string $h tml contains a paragraph with an emphasized text and an Link. Use the '/1*>/' regular expression again to replace all HTML tags and output the result.

Summary

Regular expression is a powerful tool that can help us achieve various functions in text processing, including replacing HTML tags. In PHP, it is very simple to replace HTML tags through the preg_replace() function. You only need to use a simple regular expression to quickly remove HTML tags. I hope this article can help you and enable you to better understand and apply regular expressions.

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