What are some common methods for validating user input in PHP, specifically when using the $_GET superglobal?

When working with user input from the $_GET superglobal in PHP, it is important to validate the data to prevent security vulnerabilities such as SQL injection or cross-site scripting attacks. Common methods for validating user input include using filter_input() function with FILTER_SANITIZE_STRING or FILTER_VALIDATE_INT filters, regular expressions, or custom validation functions. 

// Example of validating user input from the $_GET superglobal using filter_input()
$user_input = filter_input(INPUT_GET, 'user_input', FILTER_SANITIZE_STRING);

if ($user_input) {
    // User input is valid, proceed with further processing
} else {
    // Handle invalid input
}

Keywords

PHP user input validation $_GET superglobal filter_input validation functions

Related Questions