What potential pitfalls should PHP beginners be aware of when validating form inputs like email or phone number?

One potential pitfall for PHP beginners when validating form inputs like email or phone number is not using proper validation functions. To avoid this, beginners should use built-in PHP functions like filter_var() with the FILTER_VALIDATE_EMAIL and FILTER_VALIDATE_INT constants for email and phone number validation, respectively. 

$email = $_POST['email'];

if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
    echo "Invalid email format";
}
```

```php
$phone = $_POST['phone'];

if (!filter_var($phone, FILTER_VALIDATE_INT)) {
    echo "Invalid phone number format";
}

Keywords

PHP form validation email validation phone number validation error handling

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