What are some common pitfalls to avoid when validating user input in PHP, especially when dealing with variable data formats?

One common pitfall when validating user input in PHP, especially with variable data formats, is not accounting for different data types or formats that users may input. To avoid this, it's important to use appropriate validation functions or regular expressions to ensure the input matches the expected format. Additionally, always sanitize user input to prevent SQL injection or other security vulnerabilities. 

// Example of validating user input for an email address
$email = $_POST['email'];

if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
    // Invalid email format
    echo "Invalid email address";
} else {
    // Valid email format
    // Further processing or saving to database
}

Keywords

filter_var data validation sanitization input validation error handling

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