What is the difference between using stripslashes() and nl2br() in PHP for processing user input?

When processing user input in PHP, it's important to handle special characters properly to prevent security vulnerabilities or unexpected output. The stripslashes() function is used to remove backslashes from user input, which can be useful if the input contains escaped characters. On the other hand, nl2br() is used to insert HTML line breaks (<br>) before all newlines in a string, which can be helpful for displaying user input in a web page with proper line breaks.

// Using stripslashes() to remove backslashes from user input
$userInput = $_POST['user_input'];
$cleanedInput = stripslashes($userInput);

// Using nl2br() to insert HTML line breaks before newlines in user input
$userInput = $_POST['user_input'];
$cleanedInput = nl2br($userInput);