Exercise 4 System calls and Introduction to C++

NWEN 241 Exercise 4
System calls and Introduction to C++

Objective:
The objective of this exercise is to write and debug C programs that involve process
management & socket programming, and provide an introduction to C++ .
At the end of this exercise, you should submit the required files to the Assessment System
(https://apps.ecs.vuw.ac.nz/submit/NWEN241/Exercise_4) on or before the
submission deadline. You may submit as many times as you like in order to improve your
mark before the final deadline. Submissions beyond the deadline will not be marked and
will receive 0 marks.
Exercise Requirements
For NWEN 241, it is highly recommended that you undertake all development using the
computers in CO246. The computers in this lab use the Linux operating system. This
guide is written with the assumption that you are in CO246 lab.
If you are not able to go the lab, you can remotely access similar computers via secure
shell (ssh). Consult one of the remote study guides (see https://ecs.wgtn.ac.nz/
Courses/NWEN241_2023T1/RemoteStudyGuides) and follow one that suits you the
most.
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NWEN 241 2023-T1 System calls and Introduction to C++ Exercise 4
Exercises
Activity 1: Process Management [30 Marks]
Copy and paste the following C program to your favorite text editor:
1 #include<stdio.h>
2 #include<unistd.h>
3 #include<sys/types.h>
4 #include<sys/wait.h>
5 #include<stdlib.h>
6
7 int main()
8 {
9 int pid, ret_exec, status;
10 pid=fork();
11
12 switch(pid){
13
14 case -1:
15 /* code for case -1 */
16
17 case 0:
18 /* code for case 0 */
19
20 default:
21 /* code for case default */
22 }
23 }
Save the file as activity1.c. Study the source file and complete the program by adding
suitable code segments in the three switch case blocks as defined below:
1. case -1: Display error message - Error and exit from the program
2. case 0: Use execl system call to execute the ps -A command. If the exec system
call is unsuccessful, display an error message - Error executing exec
3. default: Wait for termination of the child process, then if WIFEXITED(status) is
set display the following values (in the same order):
• process ID of the parent process
• process ID of the child process and
• the termination status of the child process.
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NWEN 241 2023-T1 System calls and Introduction to C++ Exercise 4
Do not modify the order, otherwise, the automated marking might not work
correctly.Compile and run the program. If you are happy with the program, submit it to
the Assessment System for marking.
Activity 2: Socket Programming 2 [30 Marks]
In this activity, you will write a C server program that runs on the local machine at port
number 23456. The server should be programmed to receive a string from a client and
return the reversed string back to the client. For example, suppose you simulate a Netcat
client using the command nc localhost 23456 and then send a string "Hello" to the
server; the server would return "olleH" back to the client as shown below:
nc localhost 23456
Hello
olleH
Save the program as activity2.c. If you are happy with the program, submit it to the
Assessment System for marking.
Activity 3: Introduction to C++ [40 Marks]
In this activity, you will write a C++ program to represent complex numbers1 of the form
a + bi.
Define a class complex in a namespace Complex. The class should contain the
following members:
• Private integer members a and b.
• A constructor with zero arguments and default values for a and b set to 1;
• A constructor with two arguments which will be used to initialize a and b,
respectively.
• int geta( ) and int getb() member functions that return the values of a and
b, respectively. These functions should be public.
Write a main() function that does the following:
• Declares a complex number using the default constructor (name this complex
number as c1)
1See https://mathworld.wolfram.com/ComplexNumber.html for more information about
complex numbers.
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NWEN 241 2023-T1 System calls and Introduction to C++ Exercise 4
• Declares a complex number using the parameterized constructor (name this
complex number as c2, and use 5 and 10 as the parameters)
• Displays the values of both the complex numbers. The display should look exactly
like this:
Complex number 1:a1 + b1i\n
Complex number 2:a2 + b2i\n
where a1 and b1, and a2 and b2 are the values of the members a and b of the
complex numbers. denotes a single space character.
Use two cout statements in order (the first cout displays the complex number 1 while
the second displays the complex number 2). Note that your program should not use
printf() when displaying the values of the complex numbers.
Save the program as activity3.cpp. If you are happy with the program, submit it to
the Assessment System for marking.
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