What are some best practices for handling user input validation in PHP forms?

When handling user input validation in PHP forms, it is important to sanitize and validate all user input to prevent security vulnerabilities such as SQL injection and cross-site scripting attacks. One best practice is to use PHP's filter_input() function along with filter_var() function to validate input data against predefined filters. 

// Validate user input using filter_input()
$username = filter_input(INPUT_POST, 'username', FILTER_SANITIZE_STRING);
$email = filter_input(INPUT_POST, 'email', FILTER_VALIDATE_EMAIL);

if (!$username || !$email) {
    // Handle validation errors
    echo "Invalid input data";
} else {
    // Process the form data
    // ...
}

Keywords

Sanitize Validation Filter_var htmlspecialchars Regular expressions

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