Task $1$: Lets Do Some Calculation $!!!!$ Client$-$Server Calculator $[30$ Points$]$

In this task, you need to implement a client$-$server based calculator. The client can submit any number

of queries $($i$.$e$.$ mathematical expressions$)$ to the server. The server will evaluate the client's queries

one by one and send back the answer as a response.

In this task, the main process will call fork to create a child process where child process acts as the

server and the parent $($main process$)$ acts as client. The server will respond to all queries submitted by

the client until it receives a specific terminating word $($mentioned below$)$ as a query from the client.

After receiving the specific terminating word, the server will close the communication channel and

exits. You need to use pipe to establish a communication channel between client and server.

Figure $1$: Workflow of client$-$server based calculator.Figure $1$ shows the workflow of this client$-$server based calculator using pipes. The client $($parent$)$

should read expression $($or may be terminating word$)$ from standard input device, and will display

result received from the server on standard output device as shown in the figure.

Requirement specifications for this task are as follows:

Input expression is always space separated, i$.$e$.$ blank space between operand and operator.

Input expression always starts with an operand.

Input expression can have at most $20$ operands $($i$.$e$.,$ it can have at most $19$ operators$).$

Operands in input expression may be an integer or float$/$double number.

Input expression can contain any combination of these five operators viz. $($i$)$ Addition $(+),($ii$)$

Subtraction $(-),($iii$)$ Multiplication $(*),($iv$)$ Division $(/),$ and modulo $(\%).$

When server performs calculation, it needs to follow BODMAS rule where division, multiplication

and modulo operators are at same precedence $($say precedence$-1)$ and addition and subtraction

are at precedence$-2.$ According to BODMAS, server should first perform precedence$-1$ operations

followed by precedence$-2$ operations. Among same precedence operations, server should perform

operation from left to right.

When client receives END word from STDIN, it should send a termination signal to the server to

terminate it properly.

On receiving the result of mathematical expressions from the server, client should print "RESULT:

"followed by result. As an example, if client receive $5$ from the server, then it should display

"RESULT: $5"$ on STDOUT.

Example of Input & Output:

$[$INPUT$]1+5**2-1+10$

$[$OUTPUT$]$ RESULT: $20$

$[$INPUT$]5+1-2**5+10$

$[$OUTPUT$\text{'}]$ RESULT: $6$

$[$INPUT$]$ END