Program Description $-$ Telephone directory

The purpose of this project is to implement a C$++$ program to maintain and manage a telephone

directory. The telephone directory will be used to store subscriber details $($surname$,$ name and

telephone$($s$)).$ The implementation should be done using SORTED linked lists. To manage the directory

your program should offer the following methods through a menu:

Add a new subscriber: Ask the user for the new subscriber's name, surname and telephone

number$($s$),$ organize them appropriately in a structure $($class or struct$)$ called User, and store this

structure in a linked list $($sorted with surname$+$name$)$ using dynamic memories.

Removing a phone number from a subscriber: Ask for the surname and name of the subscriber,

and the phone number to be removed and perform the removal.

Add a phone number to a subscriber: Ask for the subscriber's surname and name, the phone

number to be added, and add it$.$

Display a subscriber's phone numbers: Ask for the subscriber's surname and name, and display

all the subscriber's phones numbers.

Delete a subscriber: Ask for the subscriber's surname and name and delete the record

associated with that name.

Sorted display of directory items by Surname$-$Name: Print all directory items sorted in

alphabetical order by subscriber surname and then name.

Exit: Your program should save all the entries in the table to the file specified at the start of the

program $($as described in the next paragraph$)$ and terminate it$.$