What are some potential security risks associated with allowing users to input data directly into PHP code?

Allowing users to input data directly into PHP code can lead to security risks such as code injection attacks, where malicious code is inserted into the input fields to manipulate the behavior of the application. To mitigate this risk, it is important to validate and sanitize user input before using it in PHP code. This can be done by using functions like htmlspecialchars() to escape special characters and prevent code injection.

$user_input = $_POST['user_input'];
$validated_input = htmlspecialchars($user_input);
echo "User input: " . $validated_input;