PHP regular expression practice: clearing HTML tags

PHP is a scripting language mainly used for web programming. It is widely used in web page production, especially in data processing, input verification and page production. Regular expressions are one of the tools frequently used by PHP programmers. This article will introduce how to use PHP regular expressions to clear HTML tags.

HTML tags are one of the necessary elements in web pages, but in some cases, it is necessary to clear HTML tags in web pages to obtain plain text content, such as obtaining text content from news websites.

The process of clearing HTML tags using PHP regular expressions is as follows:

1. There are essentially two types of HTML tags in a file:

(1) Plain text tags, such as e388a4556c0f65e1904146cc1a846bee, 0c6dc11e160d3b678d68754cc175188a, etc., their function is only to format display;

(2) Compound tags, such as dc6dce4a544fdca2df29d5ac0ea9906b, etc., their function Is a container that can be composed of parent tags and child tags.

2. First, use PHP's preg_replace function to find all Html tags:

<?php
//需要处理的字符串
$str = "<p>这里有一些 <b>加粗</b> 以及一些 <i>斜体</i> 内容。<br/></p>";
//使用正则表达式删除字符串中的 HTML 标记
$str = strip_tags($str);
echo $str; //输出：这里有一些 加粗 以及一些 斜体 内容。
?>

The strip_tags function is used in the above code to replace HTML tags. Strip_tags is a string of PHP Function to remove HTML tags from a string. The first parameter of this function is the string to be processed, and the second parameter is the HTML tag to be retained.

3. Then you can get plain text without HTML tags.

The above method can basically clear HTML tags, but in the actual process, some special situations may occur such as comment tags, etc., so a more rigorous way is to use regular expressions (Regular Expression ) to clear HTML tags. The following is a basic implementation method:

<?php
//需要处理的字符串
$str = "<p>这里有一些 <b>加粗</b> 以及一些 <i>斜体</i> 内容。<br/></p>";
//使用正则表达式删除字符串中的 HTML 标记
$str = preg_replace("/<.+?>/i","", $str);
echo $str; //输出：这里有一些 加粗 以及一些 斜体 内容。
?>

The above code uses PHP's preg_replace function and passes in parameters. "/3cb92f53558795cf450ddd50710f9912/i" is a Regular expression. The meaning of this regular expression is:

(1)c344555b90c740e0d12635e07ea03035 is the syntax symbol that matches HTML tags;

(2). ? matches any character inside the brackets, at least times .

The method of using regular expressions to delete HTML tags in strings is more rigorous and reliable than the strip_tags function, and can be applied to more complex HTML codes.

In practical applications, clear HTML tags are generally used together with other text processing methods, such as keyword extraction, text summarization, etc. Due to the uncertainty of the HTML format, in many cases it is necessary to use the elimination method for processing. If you need a more rigorous processing method, you can use tools such as html2text to achieve more accurate results.

In short, PHP regular expression clearing HTML tags is a basic data processing method and one of the essential skills for developers and data scientists.

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