In what ways can user input validation be improved to prevent unexpected formatting issues in PHP?

User input validation can be improved by using PHP functions like `filter_var()` with appropriate flags to ensure that the input matches the expected format. Regular expressions can also be used to validate input against specific patterns. Additionally, sanitizing input using functions like `htmlspecialchars()` can help prevent unexpected formatting issues. 

// Example of using filter_var() to validate email input
$email = $_POST['email'];

if (filter_var($email, FILTER_VALIDATE_EMAIL)) {
    // Valid email address
} else {
    // Invalid email address
}

Keywords

input validation formatting issues PHP regular expressions error handling

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