Description :

A.It is multi-user contact management system

B.Completely written in C++

C.Data is stored permanently using file handling in C++

A.User can login with username and password

B.New user can be created

C.Each user have its own account and private contact file

D.Data stored permanently using file handling

Each user can do:

A.Add new contact

B.Remove a contact

C.how all contacts list

D.Logout

Validation of User choices,validation of Mobile number entered by user handled Hence make it crash free.

1.Oops concepts

A.Classes 

B.Inheritance 

C .Constructor overloading 

D.Destructors etc..

2.Data file handling

A.Creating new file

B.Reading file

C.Writing in file

D.Copying file content

E.Removing files

F.Renaming files

3.Basic C++ Functions and logics