What are common issues with PHP scripts that handle language selection on multi-language websites?

One common issue with PHP scripts handling language selection on multi-language websites is not properly sanitizing user input, which can lead to security vulnerabilities like SQL injection. To solve this, always validate and sanitize user input before using it in queries or outputting it to the page.

// Example of sanitizing user input for language selection
$allowedLanguages = ['en', 'es', 'fr']; // Define an array of allowed languages

if (isset($_GET['lang']) && in_array($_GET['lang'], $allowedLanguages)) {
    $selectedLanguage = $_GET['lang'];
    // Use $selectedLanguage in your code
} else {
    // Default to English or handle the error accordingly
}