In this programming assignment, you will implement a client process and a server process, respectively, to

communicate with each other.

You can use either C$,$ C$++,$ or Java, or Python to program this project.

Your client program and server program should operate as follows. Your server runs first on a terminal waiting

for your client to connect. The server should use a server port number choosing by yourself and must be bigger

than $1024($smaller than $65535).$ Your client runs on another terminal.

Objective$---$Simple math calculator: The client program repeatedly requires the user to input a basic math

computing question, which will be sent to server program where it will be computed. The result is sent back by

the server program and the client program displays it out.

Math computing question has this format: $$x op y $=,$ where x and y are positive real numbers, $$op$$ represents

math operator of $+,-,*,/.$ The user ends the repeated input procedure by typing $0/0=.$ If the user types

in an invalid math question, the client should show an error message $$Input error. Re$-$type the math question

again.$$

The server should output the math questions sent by the client, and show the end of client input when receiving

$0/0=,$ and then shut down. An example interaction between the client and the server is shown below $($red

colored text are user input parts$)$:

Client Side:

Server Side:

Connected with server on $[$IP address$]$

$20+10\mathrm{.}5=$

Answer from server: $30\mathrm{.}5$

$13/4=$

Answer from server: $3\mathrm{.}25$

$0/0=$

User input ends; end the client program

Connected by client on $[$IP address$]$

Received question $20+10\mathrm{.}5=$; send back answer $30\mathrm{.}5$

Received question $13/4=$; send back answer $3\mathrm{.}25$

Received question $0/0=$; end the server program

When you submit this assignment to me$,$ please submit the following $($put in a $.$zip file$)$:

$$ A brief report: write a brief description of your program codes, then copy the screen output images in

your report, showing your client running screen and server running screen $($must be screen shot images,

not the text you directly copy and paste onto your report$).$ Your client and server interaction must show

each of those four types of math operations at least once.

$$ Submit client source code and server source code as attachments in the Blackbord submission page. I will

try to download and run your code by myself. Be sure to explain clearly in your report how to compile

and run your code!

CE $3761$: Computer Network Systems

Homework $3($Spring $2024)$

Assigned Mar. $16$h; Due midnight Mar. $28$th via Blackboard

Programming notes

Here are a few tips to help you with the assignment:

$$ If you code using C language, use this command line to compile your C program to generate the

executable file:

gcc $-$o client client.c $($or gcc $-$o server server.c$)$

$$ The machine IP address will be $$localhost$$

$$ You must chose a server port number great that $1024($to be safe, choose a server port number larger than

$5000).$ If you choose a port that is using currently by another user's server program, you have to choose

another port.

$$ Make sure you close every socket that you use in your program before your program ends. If you abort

your program, the socket may still hang around and the next time you try and bind a new socket to the

same port number you previously used $($but never closed$),$ you may get an error "Address already in

use". If this happens, you have to wait a minute or so to let the hanging socket time out, or use a different

port number.

$$ Be aware that port ID's, when bound to sockets, are system$-$wide values and thus other students may be

using the port number you are trying to use.