What are some common pitfalls to avoid when working with PHP forms and dynamic elements?

One common pitfall when working with PHP forms and dynamic elements is not properly sanitizing user input, which can lead to security vulnerabilities such as SQL injection or cross-site scripting attacks. To avoid this, always use functions like htmlspecialchars() or mysqli_real_escape_string() to sanitize user input before using it in your code. 

// Sanitize user input using htmlspecialchars()
$name = htmlspecialchars($_POST['name']);
$email = htmlspecialchars($_POST['email']);
```

Another common pitfall is not validating user input, which can result in unexpected behavior or errors in your application. To prevent this, always validate user input using functions like filter_var() or regular expressions to ensure it meets the expected format.

```php
// Validate email input using filter_var()
if (filter_var($_POST['email'], FILTER_VALIDATE_EMAIL)) {
    // Email is valid
} else {
    // Email is not valid
}
```

Lastly, be cautious when dynamically generating HTML elements using user input, as this can open your application to cross-site scripting attacks. To mitigate this risk, always escape user input when echoing it in HTML to prevent malicious scripts from being executed.

```php
// Escape user input when echoing in HTML
echo "<p>" . htmlspecialchars($_POST['comment']) . "</p>";

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