How to use "code" in a sentence

Each time, Leti typed in a complicated code to let them in, as well as waiting by the recognition screen

In the locked center drawer of the desk was a book with the code numbers that permitted access to the sensitive information stored not on diskette but only in the central memory

Tina paged through the book until she found the code that she needed to call up the list of the hotel's best customers

She typed in the code for the list of complimentary guests, and the machine responded at once.