How to remove tags and various special characters in php

When writing PHP programs, you often need to deal with tags and special characters in strings. This is a common task for web developers, as web applications often need to receive data from user input and store or display it in the page. During this process, problems with character sets and tags will surface, so we need to learn how to remove them.

1. How to remove HTML tags in PHP

First of all, we need to make it clear that PHP provides many methods to remove HTML tags, but these methods often affect Other special characters of the string. For example, using the strip_tags() function can remove HTML tags, but it will not remove other seemingly non-standard tags, such as JavaScript and CSS code. Therefore, we need a more comprehensive approach to deal with this problem.

Here is a method:

function remove_html_tags($str)
{
    return preg_replace('/<(.*?)>/u', '', $str);
}

$str = 'This is a <b>bold</b> text with HTML <i>and italic</i> tags.';
echo remove_html_tags($str);

This function uses a regular expression to match HTML tags and replace them with empty strings. Note that we used the '/u' identifier, which means matching in Unicode mode for better handling of Chinese character sets.

2. Remove special characters from the string

In addition to HTML tags, we may also need to remove other special characters from the string, such as line breaks and tabs. characters and carriage return characters, etc. Here is a simple function that removes all these special characters:

function remove_special_chars($str)
{
    return preg_replace("/[\n\t\r]/", '', $str);
}

$str = "This is a string\nwith\nnewlines\tand\ttabs.";
echo remove_special_chars($str);

This function uses a regular expression to match all newlines, tabs, and carriage returns and replace them with Empty string. Of course, you can also add or delete other special characters according to actual needs.

3. Comprehensive processing method

Finally, we combine these two methods to better handle HTML tags and special characters in strings. The following function can achieve this function:

function remove_html_and_special_chars($str)
{
    $str = remove_html_tags($str);
    $str = remove_special_chars($str);
    return $str;
}

$str = "This is a <b>bold</b> text\nwith HTML <i>and italic</i> tags,\nand newlines and\ttabs.";
echo remove_html_and_special_chars($str);

This function first uses the remove_html_tags() function to remove HTML tags, and then uses the remove_special_chars() function to remove special characters. In this way, we can get a plain text string without any HTML tags and special characters.

Summary

In the process of writing PHP, processing HTML tags and special characters in strings is a common task. This article introduces some methods for removing HTML tags and special characters, and how to use them combined to achieve better results. Of course, this is just a basic processing method, and the specific implementation method needs to be selected based on the needs of the actual project.

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