What are the best practices for sanitizing and validating user input in PHP to prevent security breaches?

When dealing with user input in PHP, it is crucial to sanitize and validate the data to prevent security breaches such as SQL injection or cross-site scripting attacks. Sanitizing involves removing any potentially harmful characters or code from the input, while validation ensures that the data meets the expected format or criteria. Using functions like htmlspecialchars() to sanitize input and regular expressions or built-in PHP functions like filter_var() for validation can help mitigate these risks. 

// Sanitize user input
$sanitized_input = htmlspecialchars($_POST['user_input']);

// Validate user input (example: ensuring it is a valid email address)
if (filter_var($_POST['email'], FILTER_VALIDATE_EMAIL)) {
    // Input is valid
} else {
    // Input is not valid
}

Keywords

filter_input htmlspecialchars prepared statements CSRF protection input validation

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