The call by reference method of passing arguments to a function copies the address of an argument into the formal parameter. Inside the function, the address is used to access the actual argument used in the call. It means the changes made to the parameter affect the passed argument.

(Quelle: https://www.tutorialspoint.com/cprogramming/c_function_call_by_reference.htm, Einsichtsdatum: 23.12.2019)