What are some best practices for handling user input in PHP to prevent SQL injection and XSS vulnerabilities?

To prevent SQL injection, it is best practice to use prepared statements with parameterized queries instead of directly inserting user input into SQL queries. To prevent XSS vulnerabilities, user input should be properly sanitized and validated before being displayed on a webpage. 

// SQL injection prevention using prepared statements
$stmt = $pdo->prepare("SELECT * FROM users WHERE username = :username");
$stmt->bindParam(':username', $_POST['username']);
$stmt->execute();
```

```php
// XSS prevention using htmlspecialchars function
echo "Welcome back, " . htmlspecialchars($_POST['username'], ENT_QUOTES, 'UTF-8');

Keywords

SQL injection XSS vulnerabilities user input validation prepared statements htmlspecialchars

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