COMPILE::
gcc data.c -o data       
gcc server.c -o server
gcc client.c -o client

RUN::
./data    ---  only used to add the initial data/records into files.
./server  ---  first in one terminal
./client  ---  in the other terminal

CLIENT::
1.You have three options : Normal User login, Joint User login, Admin login.
2.Login with your credentials.
3.If successful you get different options then you choose one of them to perform its action.

SERVER::
1.The server checks the login credentials entered by the client.
2.Performs the actions chosen by the client.
3.Implements suitable write and read locks when required.