How can environment variables be set in PHP to access Google API credentials?

To set environment variables in PHP to access Google API credentials, you can use the `putenv()` function to set the variables before making the API call. This allows you to securely store sensitive information like API keys and credentials outside of your codebase.

// Set Google API credentials as environment variables
putenv('GOOGLE_API_KEY=your_api_key_here');
putenv('GOOGLE_CLIENT_ID=your_client_id_here');
putenv('GOOGLE_CLIENT_SECRET=your_client_secret_here');

// Access the environment variables
$apiKey = getenv('GOOGLE_API_KEY');
$clientID = getenv('GOOGLE_CLIENT_ID');
$clientSecret = getenv('GOOGLE_CLIENT_SECRET');

// Make API call using the credentials
// Example:
// $client = new Google_Client();
// $client->setDeveloperKey($apiKey);
// $client->setClientId($clientID);
// $client->setClientSecret($clientSecret);