How can I sanitize user input with PHP?

There are several ways to sanitize user input in PHP, depending on the type of data and how you plan to use it. Here are some common methods:

1. Use htmlspecialchars() to encode special characters in HTML. This is useful when you want to display user input as HTML and want to prevent script injection attacks.

2. Use strip_tags() to remove HTML and PHP tags from a string. This is useful when you want to allow users to format their input with basic HTML tags, but want to remove potentially malicious tags.

3. Use trim() to remove leading and trailing whitespace from a string. This is useful for cleaning up user input, especially when you are expecting a specific format (e.g. a username or password).

4. Use addslashes() to add backslashes to a string. This is useful when you are storing user input in a database and want to prevent SQL injection attacks.

5. Use filter_var() with a specific filter flag to sanitize user input. For example, you can use FILTER_SANITIZE_EMAIL to remove all illegal characters from an email address.

It's important to note that sanitizing user input does not guarantee that it is safe to use. You should always validate user input to