In the context of PHP programming, what are some best practices for handling user input from forms to ensure data integrity and security?

When handling user input from forms in PHP, it is crucial to validate and sanitize the data to ensure data integrity and security. One common best practice is to use PHP's built-in functions like filter_input() and filter_var() to sanitize input and prevent SQL injection attacks. Additionally, always validate the input against expected formats and lengths to prevent malicious input. 

// Example of sanitizing user input using filter_input()

$username = filter_input(INPUT_POST, 'username', FILTER_SANITIZE_STRING);
$email = filter_input(INPUT_POST, 'email', FILTER_VALIDATE_EMAIL);

// Example of validating input against expected formats

if (strlen($username) < 3 || strlen($username) > 20) {
    // handle error, username must be between 3 and 20 characters
}

if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
    // handle error, invalid email format
}

Keywords

validation sanitization prepared statements CSRF protection input filtering

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