Generally, the following guidelines should be observed by computer users:
(i) Honesty: Users should be truthful while using the internet.
(ii) Confidentiality: Users should not share any important information with unauthorized people.
(iii) Respect: Each user should respect the privacy of other users.
(iv) Professionalism: Each user should maintain professional conduct.
(v) Obey The Law: Users should strictly obey the cyber law in computer usage.
(vi) Responsibility: Each user should take ownership and responsibility for their actions.

Encryption and decryption are processes that ensure confidentiality that only authorized persons can access the information.
Encryption is the process of translating the plain text data (plaintext) into random and mangled data (called cipher-text).
Decryption is the reverse process of converting the cipher-text back to plaintext. Encryption and decryption are done by cryptography. In cryptography a kev is a piece of information (parameter) that determines the functional output of a cryptographic algorithm.

Some Facts About the execution of constructor in inheritance
i. Base class constructors are executed first, before the derived class constructors execution
ii. Derived class cannot inherit the base class constructor but it can call the base class constructor by using Base_class name::base_class_constructor() in derived class definition
iii. If there are multiple base classes, then its start executing from the left most base class
iv. In multilevel inheritance, the constructors will be executed in the order of inheritance The destructors are executed in the reverse order of inheritance.

Polymorphism	Inheritance
Reusability of code is implemented through functions (or) methods.	Reusability of code is implemented through classes.
Polymorphism is the ability of a function to respond differently to different message.	Inheritance is the process of creating derived classes from the base class or classes.
Polymorphism is achieved through overloading.	Inheritance is achieved by various types of inheritances namely single, multiple, multilevel, hybrid and hierarchical inheritances.

Function overloading can be applied for constructors, as constructors are special functions of classes. A class can have more than one constructor with different signature. Constructor overloading provides flexibility of creating multiple type of objects for a class.
1. Memory is allocated for the objects.
2. Initialisation for the objects.

When constructor and destructor are declared under public:
1. we can initialize the object while declaring it.
2. we can explicitly call the constructor.
3. we can overload constructors and therefore use multiple constructors to initialize objects automatically.
4. we can destroy the objects at the end of the class scope automatically (free unused memory). 
However, some C++ compilers and Dev C++ do not allow to declare constructor and destructors under private section. So it is better to declare constructor and destructor under public section only.

Given Program	Corrected Program	Corrections
#include $include class mystud { int studid =1001; char name[20]; public m ystud( ) { } void register ( ) {cin>>stdid; gets(name); } void display ( ) {cout< } int main( ) { mystud MS; register.MS( ); MS.display( ); }	#include #include using namespace std: class mystud {int studid; public: void register () {cin>>studid;get(name); } {cout< }; int main() } {mystud MS; MS.register1(); MS.display(); }	missing line space between class and class name space between int and studid, studid cannot be initialized here : (colon) is missing // register is a keyword-cannot be used as function name // data member is should be studid // wrong syntax & method name

Modularization: where the program can be decomposed into modules.
Software re-use: where a program can be composed from existing and new modules.

1. Programs are organized in the form of subroutines or sub programs.
2. All data items are global.
3. Suitable for small sized software application.
4. Difficult to maintain and enhance the program code as any change in data type needs to be propagated to all subroutines that use the same data type. This is time consuming.
Example: FORTRAN and COBAL.

}
struct student
int exam_no, lang, eng, phy, chem, mat, csc, total;
char name [15];
}
int main()
{
students [20];
for (int i = 0; i <20; i++)
{
cout<<"\n Enter the exam number of student:"";
cin>> s[i].exam_no.;
cout << "\n Enter language names:";
ein>>s[i].lang;
cout<<"Enter name of the Student:"";
cin>>s[i].Name;
}
for (int i=0; i<20; i++)
{
if (s[i],name[0] == 's')
{
cout << "Exam number:" << s[i].name;
cout << "Student Exam number";
}
}
return 0;}

#include< iostream >
using namespace std;
int main()
{
char name[20];
cout << "Enter your name'' << endl;
cin.get(name,20);
cout << "Your name:" << name«endl;
return 0;
}
output:
Enter your name : xxxx xxxx
Your name: xxxx xxxx

Given Code	Functional Code
v = 5; do; { total += v; cout << total; while v <= 10	int v = 5, total = 0; do { total + = v; cout << total; V++; } while (v<=10);

C++ program is a collection of functions. Every C++ program must have a main function. The main() function is the starting point where all C++ programs begin their execution. Therefore, the executable statements should be inside the main() function.

Syntax error	Logical error
The syntax is a set of grammatical rules to construct a program. Every programming language has unique rules for constructing the source code. Syntax errors occur when grammatical rules of c++ are violated.	A Program has not produced the expected result even though the program is grammatically correct. It may happen by the wrong use of variable/operator/order of execution etc. This means, the program is grammatically correct, but it contains some logical errors. So, Semantic error is also called as "Logic Error".

Operator	Operation	Result
^	a^b	00001010 a
		00001111 b
		00000101 a^b
a^b = (00000101)2 = 510

C++ is a case sensitive programming language so, all the keywords must be in lowercase. Case sensitive means that the uppercase and lowercase letters are considered differently.

S1; S2; S4

No. of players	2	3	4	5	n	1234
No. of games	1	2	3	4	n - 1	1234 - 1 = 1233

On the other hand let n be the number of games played and r be the number of players remaining in the tournament.
After every game, r will be reduced by 1.
r → no. of players remaining
n → no. of games played
If r=2 then n=1
As n increases, r decreases
n,r: n+1,r-1
n+r=(n+1)+(r-1)
= n + 1 + r - 1
= n + r
Therefore n + r is invariant.
n+r=1234 (No. of players initially)
The winner of the tournament is the player that is left after all other players have been knocked out.
After all the games, only one player (winner) is left out.
i. c. n = 1
Put n = 1 in (1)
n+r=1234 ....(1)
1+r=1234
r = 1234-1-1233
No. of games played = 1233

Assignment statement is used to assign values to the variables.
The variable on the left side of the assignment operator and a value on the right side.
Variable := Value

Abstraction :
It is the facility to define objects. It also involves removal of unnecessary attributes and defining only essential attributes.
For example, when we represent the state of a process we select only the variables essential to the problem and ignore inessential details.

CD	DVD
CD stands for Compact Disc	DVD stands for Digital Versatile Disc
Can store up to 700 MB	Capacity of DVD is 4.7 GB of data
CD's are single sided	DVD's are single or double sided
Due to capacity constraint, CD's cannot store movies of good quality	DVD's are used for storing movies with good quality
CD players cannot play DVD's	DVD players can play CD's

Windows OS	Linux OS
It is a commercial licensed OS.	It is a open source OS.
Only one distributor	Many distributors
It uses GUI	It uses kernel.
It boot only from primary partition	It boot either from a primary or from a logical partition.
Secure	Insecure.

Impact printers:
(i) Impact printer refers to the class of printers that work by banging a head or needle against an ink ribbon to make a mark on the paper.
(ii) Impact printers are very noisy.
(iii) These printers can print on multi-part.
Eg: Dot Matrix, Line printers.

The three output devices are
(a) Plotter
(b) Speakers
(c) Multimedia Projector.
(i) Plotter:
Plotter is an Output device that is used to produce graphical Output on papers. It uses single colour or multi-colour pens to draw pictures.
(ii) Speakers:
Speakers produce voice output (audio). Using speaker along with speech synthesize software, the computer can provide voice output.
(iii) Multimedia Projector:
Multimedia projectors are used to produce computer output on a big screen. These are used to display presentations in meeting halls or in classrooms.

Applications of Computer: Banking, Insurance, Education, Marketing, Health care, Engineering design, Communication, Government, Weather forecasting.