PHP strip_tags()

Including Allowable Tags

Sometimes, we might want to keep certain HTML tags for text formatting purposes. This is where the $allowable_tags parameter comes into play.

<?php
$text = "<h1><p>Hello, World!</p></h1>";
echo strip_tags($text, '<p>');
?>

The output here would be: <p>Hello, 

World!</p>

Security Implications

While strip_tags() is a useful function for quick-and-dirty tag removal, it's not a foolproof solution for preventing XSS attacks. There are many ways for malicious users to bypass this function, such as using unconventional casing, embedding null bytes, or using short open tags.

For comprehensive sanitation of user inputs, functions like htmlentities() or htmlspecialchars() should also be used.

Frequently Asked Questions 

What does the PHP strip_tags() function do?

The strip_tags() function removes HTML and PHP tags from a string.

Can I allow certain tags to remain using strip_tags()?

Yes, you can specify allowable tags as the second parameter to strip_tags().

Is strip_tags() sufficient to prevent XSS attacks?

No, strip_tags() is not a comprehensive solution for XSS. Other functions like htmlentities() or htmlspecialchars() should also be used.

Conclusion

The strip_tags() function in PHP provides a simple way to remove HTML and PHP tags from a string. It's an important tool for maintaining data integrity and reducing the risk of code injection attacks. However, while it can be part of a sanitization process, it should not be relied upon as a complete solution for preventing XSS attacks. Always consider using additional methods to ensure comprehensive data sanitation in your PHP applications.

If you would like to learn more, check out our articles on

• PHP Introduction
• Array push in PHP
• Introduction to OOP in PHP
• PHP date and time
• PHP Array

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