What are the potential pitfalls of allowing user input for phone numbers in various formats in a PHP application?

Allowing user input for phone numbers in various formats can lead to inconsistent data storage and retrieval. To solve this issue, it's recommended to normalize the phone numbers to a standard format before saving them to the database. This can be achieved by removing any non-numeric characters and ensuring a consistent format such as (XXX) XXX-XXXX. 

// Normalize phone number to (XXX) XXX-XXXX format
$userPhoneNumber = "(123) 456-7890";

// Remove non-numeric characters
$normalizedPhoneNumber = preg_replace('/\D/', '', $userPhoneNumber);

// Format the phone number
$formattedPhoneNumber = preg_replace('/(\d{3})(\d{3})(\d{4})/', '($1) $2-$3', $normalizedPhoneNumber);

echo $formattedPhoneNumber; // Output: (123) 456-7890

Keywords

SQL injection XSS attacks data validation phone number formatting input sanitization

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