What are some common pitfalls when using PHP to handle form data, specifically related to special characters and form validation?

One common pitfall when using PHP to handle form data is not properly sanitizing and validating user input, which can lead to security vulnerabilities and unexpected behavior. To avoid this, always sanitize user input using functions like htmlspecialchars() to prevent XSS attacks and validate input using functions like filter_var() to ensure it meets the expected format. 

// Sanitize user input to prevent XSS attacks
$clean_input = htmlspecialchars($_POST['input_field'], ENT_QUOTES);

// Validate input to ensure it meets the expected format
if (!filter_var($clean_input, FILTER_VALIDATE_EMAIL)) {
    // Handle invalid email input
}

Keywords

XSS htmlspecialchars htmlentities filter_input regex

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