BASIC CONCEPT OF C++

Hello, students today I am very happy to write this chapter. and I hope that you have understood very well. because I have written all the things very clearly. in this chapter, I will discuss everything about this concept of c++ programming. after studying this you acquire lots of knowledge in yourself and you have an idea about how to make the program in c++. so now let's start.

C++ is an object-oriented programming language through which we can communicate with another computer system.

It is developed by B. Jarane Stroustrup at AT&T Bell Laboratories in The USA in 1980.

Its initial name was ‘C with Classes’ and after that rename as c++ in 1983.

It is a superset of the C language.

It is an extended or incremented form of C language.

It is a case-sensitive language. i.e it treats different in uppercase & lowercase.

It is a third-generation language.

It is a high-level language.

It is a platform-independent language. i.e it supports any operating system like Windows XP, Windows 10... etc.

It is used in both writings in system software and application software.

OBJECT ORIENTED PROGRAMMING:- it is a way of programming that allows modularizing a program by forming separate memory area for data as well as function.

CHARACTERISTICS OF OBJECT-ORIENTATION PROGRAMMING:-

Programs are divided into classes and their number of functions.
New data items and functions can be easily added whenever essential.
Data is private and prevented from accessing external functions.
An object-oriented program is more focused on data than function.
An object can communicate with each other through functions.
O.O.P can be easily upgraded without affecting the other parts of the program.
Redundant program code can be eliminated using inheritance.
O.O.P allows polymorphism, encapsulation, and other characteristics.
O.O.P enhances the process of programmers to the rapid development of new software in a short time.

Uses of O.O.P

To develop Object-oriented DBMS application software.
To develop system software.
It is used to develop office automation software.
It is also used to develop A.I(artificial intelligence) and expert system.
It is used in CAD(computer-aided design)
It is used in CAM(computer-aided manufacturing).

There are following O.O.P language such as-

Ø Simular67

Ø C++

Ø Charm++

Ø Java

Ø C# .......etc

KEY CONCEPT OF O.O.P

CLASS:-

it is a user-defined data type.
Class is a group of similar objects that can share their common properties and relationship.
A class serves as a blueprint or template for its objects that are any number of objects related to the class can be created.
A class represents the data and functions.
Example – ‘fruits’ is a class and its object is banana, apple .etc.

Object:- An object is a runtime entity like a chair, pencil...etc.

Ø Object is like a variable of type class.

Ø An object consists of the state and the behaviour of related class and function.

class is a blueprint for objects. and class is also an object factory.

Method / Function:- The operation required for an object when coded in a class is called Method.

it is a set of instruction that are developed for a specific purpose to perform a particular task

Data Abstraction:- The representation of essential features without including the background details is called data abstraction.

Ø Abstraction is a mechanism or the technique to hide irrelevant(unwanted) details and representation of essential features so that one can focus on important things at a time.

Ø Example:- while driving, A driver only knew the essential features such as how to use the clutch, brake, accelerator, gears...etc.

Polymorphism :- it is a Greek word that means multiple forms.

Ø Polymorphism allows the same function to act differently.

Ø Example- function overloading, operator overloading ..etc.

Encapsulation :- The packing of data and function into a single component are known as encapsulation.

Inheritance:- it is the method or technique by which objects of one class get the properties of the object of another class.

Ø Inheritance allows us to derive a new class from an existing class.

Structure of the C++ program

file section

Class class-name

{

Private:

Data member

Member function

Public:

Data member

Member function

Protected:

Data member

Member function

};

Void main()

{

.....................

Statement

}

Tokens:-The smallest individual unit of the program is known as tokens.

FThere are following types of tokens such as:-

Keyword
Identifier/variable
Constant/literal
Operator
Special character/ separator/ punctuator

Keyword :- A keywords have a fixed meaning and these meanings can not be changed. There are 63 keywords in c++, keywords are reserve words for the system. So, these are also known as reserve words.

Keywords are the predefined words that have special significance and importance.
Keyword can not be used to declare a variable name, class name, function name, and object name.

F There are following keyword listed below –

char	short	int	long
enum	true	false	double
float	void	struct	union
typedef	signed	unsigned	volatile
register	const	Static	extern
auto	static cast	dynamic-cast	const - cast
if	else	switch	case
default	for	while	do
break	continue	return	goto
new	delete	class	friend
private	public	protected	template
virtual	operator	this	try
throw	catch	using	namespace
sizeof	inline	wchar-t	reinterpret-cast
type id	type name	mutable	explicit
boolean	export

| Identifiers:- the meaningful variable name, the function name is known as identifiers.

F An identifier is a user-defined word.

F Example – length, sum, area, height.

| Variable :- it is a data name that holds data value.

F It allocates the memory location to the value.

F It is like a container of data.

F There are following rules for defining variable name or identifier-

Variable name must begin with a character without space but underscore is permitted.

The variable the name should not start with a digit.

The variable name may be a combination of uppercase and lowercase characters.

Variable should not be a c++ keyword.

The length of the variable name may up to 31-character.

Visibility mode/ access specifier:- it determines which data where to access.

There are three access specifiers or visibility mode in c++ such as –

1. Private

2. Public

3. Protected

1. Private:- Data member and member function declared under this section can not be accessible outside of the class.

Ø If there are no access specifiers declared then by default takes private access specifier.

2. Public:- Data member and member functions declared under this section can be accessed outside of the class.

3. Protected:- Data member and member functions declared under this section can be accessed outside of the class in inheritance.

NOTE:- Data member:- A variables declared inside the class is called data member or member variable.

Member function:- A function declared inside the class is called member function.

Constant:- constant refers to fixed value and value cannot be changed during the program execution.

Ø It is also known as literals.

Ø We use the ‘const’ keyword for declaring constant.

Ø We can also use the #define for declaring constant.

Ø E.g. #define a 10

Ø There are two types of constant such as –

1. Numeric

2. Character

1. Numeric constant:- it is a negative or positive numeric value that is either an integer or fractional constant.

2. Character constant:- it is one or more characters that are enclosed within single quotes.

e.g:- ‘A’ ‘B’......etc

Ø String constant also belongs to this character constant is always written within double quotes.

Ø E.g – “vmsm”

3. Operator:- An operator is a symbol that performs particular operation between the operands( like addition, subtraction, division, multiplication etc.)

E.g- S= A+B, here both A, B are the operands and the ‘+’ sign is an operator.

Ø There are three types of the operator such as-

1. Unary operator

2. Binary operator

3. Ternary operator

| Unary operator:- An operator which are required one operand to perform a particular task.

Ø There are two unary operators such as-

1. Incremented operator ( ++)

2. decremented operator (--)

E.g- A++ , A-- , ++B , --B.

Increment & decrement operator:- -

Ø This operator works as a shorthand tool to increase or decrease the value of the variable by one.

Ø “++” increase the value of a variable by one. i.e. i++= i+1.

Ø “- -“ decrease the value of a variable by one. i.e. i-- = i-1.

Ø These operators can be used in two ways such as-

1. Pre increment or post-increment

2. Pre decrement or post decrement

1. Pre increment or pre decrement:- when the operator is placed before operands then this is known as pre-increment or pre decrement operator.

E.g- ++a , --a

Ø It process first then incremented or the decremented value will be assigned to any term.

2. Post increment or post decrement:- when the operator is placed after operands then this is known as post-increment or post decrement.

E.g.- a++ , a--.

Ø It receives value as it is then incremented or decremented value will be share to any term.

Q. write a program in c++ by using increment or decrement operator .

#include<iostream.h>

#include<conio.h>

void mian()

{

clrscr();

int n=10, S,T;

S= n++;

T=++n;

cout<<”S=”<<S<<”\n”;

cout<<”T=”<<T;

getch();

}

Output

| Binary operator:- those operators which are required two operands to perform any task.

e.g.- A+B, where A, B both are

operands and + sign is an operator.

Ø There are following binary operator such as-

+,-,* , / , %.....etc.

Q. write a program to find addition, subtraction, and multiplication, and division.

#include<iostream.h>

#include<conio.h>

void main()

{

clrscr();

int A=10, B=20, sum, sub, mult;

sum=A+B;

cout<<"sum=";

cout<<sum;

sub=B-A;

cout<<"\n subtraction=";

cout<<sub;

mult=A*B;

cout<<"\n multiply=";

cout<<mult;

getch();

}

output

sum=30

subtraction=10

multiply=200

| Ternary operator:- those operators which required more than two operands are known as the ternary operator.

e.g- if(n1==n2)? True : false

It is also known as conditional operator.

Example :-

#include<iostream.h>

#include<conio.h>

void main()

{

clrscr();

int x =100, z;

z=(x==100 && x==1000?1 : 0);

cout<<z;

getch();

}

Output

TYPES OF OPERATOR

There are following types of operators such as-

1. Arithmetic operator

2. Relational operator

3. Logical operator

4. Assignment operator

5. Bitwise operator

6. Conditional operator

7. Increment decrement operator

8. Special operator

1. Arithmetic operator:- it performs the basic arithmetic operations on operands.

Ø It requires a numeric value.

Ø E.g.- + , - , * , %, /

2. Relational operator:- these operators are used to distinguish between two values depending on their relations.

Ø It provides the relationship between two expressions.

Ø These are also known as comparison operator.

Ø These are used generally create conditions.

Ø E.g.- < , > , <= , >= , == , !=

3. Logical operator:- it is used to testing logical conditions between operands.

Ø These are used to combined or negate expressions. After checking conditions, it provides logical true (1) or false (0) status.

Ø E.g.- 1. logical AND(&&)

2.Logical OR(||)

3. logical NOT(!)

Logical AND (&&):- These operators provide true results when both expressions are true(1) otherwise false(0).

E.g.-

#include<iostream.h>

#include<conio.h>

void main()

{

clrscr();

int x =100, z;

z=(x==100 && x==1000?1 : 0);

cout<<z;

getch();

}

Output

Logical OR(||):- These operators provide true result when one any expressions are true(1) otherwise false(0).

e.g.-

#include<iostream.h>

#include<conio.h>

void main()

{

clrscr();

int x =100, z;

z=(x==100 ||x==1000?1 : 0);

cout<<z;

getch();

}

Output

Logical NOT (!):- these operator provides true result if input is zero(0) otherwise gives one(1).

#include<iostrteam.h>

#include<conio.h>

void main()

{

clrscr();

int x=100, z;

z=(x!=100? 1:0);

cout<<z;

getch();

}

Output

Assignment operator:- it is used to assigning the value to the variable.

e.g.- a=5

there are some assignment operator such as

= , <= , >= , /=, %= , +=, -=, <<= , >>=, >>>= , &= , !=, ^=

#include<iostrteam.h>

#include<conio.h>

void main()

{

clrscr();

int x=10, z;

if(x>=10)

{

cout<<” true”;

}

else

{

cout<<” false”;

}

getch();

}

Output

true

Bitwise operator:- this operator is used to a bit manipulation and can only be applied to integer operands.

Ø There are following bitwise operator such as-

& - bitwise AND

| - bitwise OR

^ - bitwise XOR

~ - bitwise NOT

>> - right shift

<< - left shift

Bitwise AND:- it returns 1. if both the bits are 1 and it returns zero if one any the bit will be zero.

E.g.-

#include<iostream.h>

#include<conio.h>

void main()

{

clrscr();

int a, b,c ;

a=15;

b=9;

c=a&b;

cout<<”c=”<<c;

getch();

}

Output

Bitwise OR(|):- it returns 1 if anyone bit is 1. otherwise it returns zero if both bits are zero.

E.g.-

#include<iostream.h>

#include<conio.h>

void main()

{

clrscr();

int a=15, b=9,c;

c=a|b;

cout<<”c=”<<c;

getch();

}

Output

Bitwise NOT (~):- it is also known as the complement operator. It returns zero if the input bit is one. otherwise, it returns one if the input bit is zero.

include<iostream.h>

#include<conio.h>

void main()

{

clrscr();

int a=15 , c;

c=~a;

cout<<”c=”<<c;

getch();

}

Output

-16

Bitwise XOR:- it returns zero if both bits are the same. Otherwise returns one.

E.g.-

#include<iostream.h>

#include<conio.h>

void main()

{

clrscr();

int a,b,c;

a=15;

b=9;

c=a^b;

cout<<”c=”<<c;

getch();

}

Output

Commas operator:- it is used to separating variables and expressions.

Conditional operator:- it is used to checking a condition and execute any single expression according to it.

Ø There are three parts of this operator such as-

#include<iostream.h>

#include<conio.h>

void main()

{

int n;

clrscr();

cout<<”enter any number n=”;

cin>>n;

n%2==0?cout<<”even number” : cout<<”odd number” ;

getch();

}

Output

Enter any number=4

even number

v Statement - instruction is written in a high-level language or defined a task in a program is called a statement.

There are two types of statement such as-

1. Single line statement

2. Compound statement

1. Single line statement:- it determines a single task. And it is terminated with a semicolon.

2. Compound statement:- it determines multiple tasks. It is always enclosed within curly braces.

Conditional statement:- The statement which is used to create a condition of making a decision in program is known as conditional statement.

If statement :- it is a conditional statement and used for decision making. it is used in four ways such as-

1. 1.Simple if

2. 2.if else

3. 3. Nested if-else

4. 4.Ladders if else

Simple if:- it is a conditional statement. it is used to execute a set of statements if the condition is true.

Ø Multiple conditions can be combined with logical operators.

Ø It is also known as a single structure.

Syntax:-

if( test condition)

{

Statement;

}

Next statement;

Flow chart:-

Q write a program to check person is eligible for vote or not.

#include<iostream.h>

#include<conio.h>

void main()

{

clrscr();

int age;

cout<<”Enter age of person=”;

cin>>age;

if(age>=18)

{

cout<<”eligible for vote=\n”;

}

cout<<” thanks “;

getch();

}

Output

Enter the age of person=19

Eligible for vote

thanks

if-else statement:-it is a conditional statement. it is used to express or execute a different set of statements according to the true and false value of a given condition.

Ø It is similar to conditional statement.

Syntax :- if(test condition)

{

True block statement;

}

else

{

False block statement;

}

Flow chart:-

Q. write a program to print number is even or odd.

#include<iostream.h>

#include<conio.h>

void main()

{

int n;

cout<<”Enter any number=”;

cin>>n;

if(n%2==0)

{

cout<<“number is even”;

}

else

{

cout<<” number is odd”;

}

getch();

}

Output

Enter any number= 4

number is even.

Q. write a program in C to check number is prime or not.

#include<iostream.h>

#include<conio.h>

void main()

{

clrscr();

int n , i, s=0 , f=0;

cout<<”enter any number”;

cin>>n;

s=n/2;

for(i=2; i<=s; i++)

{

if(n%i==0)

{

cout<<”number is not prime”;

f=1;

break;

}

if(f==0)

{

cout<<” number is prime”;

}

Enter any number=4

Number is not prime

Nested if else:- when a series of decision are involved then we have to use more than one if-else statement in a nested form.

Ø One if-else within another if-else is known as nested if-else

Ø ‘C++’ allows 256 levels of nested if else in a program.

Syntax :-

if(test condition)

{

if(test condition )

{

Statement ;

}

else{

Statement ;

}

else{

if( test condition)

{

Statement;

}

else

{

Statement;

}

Ladder if else:- it is a conditional statement and used for decision forming when we have multiple options or cases.

Ø In this statement each ‘if’ contains an expression or evaluated from top to bottom.

Ø When a condition found true the statement associated with ‘if’ is executed and control exit from the condition.

Ø If none of the conditions is satisfied then else block is executed.

Ø Syntax:-

if(test condition)

{

Statement;

}

else if(test condition)

{

Statement;

}

else if (test condition)

{

Statement;

}

else if(test condition)

{

Statement;

}

else

{

Default statement;

}

Flow chart :-

| goto statement:- this statement is used to transfer the control from one part of the program to another part unconditionally.

Ø It is used for iterative or repetitive task.

Ø It requires a label followed by colon(:) symbol.

Ø Syntax :- goto label name;

Ø E.g.- goto vmsm;

Q. write a program to print your name five times.

#include<iostream.h>

#include< conio.h>

void main()

{

clrscr();

int i;

i=1;

vmsm:

cout<<”\n vikas mishra”;

i++;

if(i<=5)

goto vmsm;

getch();

}

OUTPUT

Vikas mishra

Q. write a program in c++ by using goto statement to print a table of the input number.

Q. write a program to find factorial of input number by using goto statement.

LOOP:- it allows execution of statements of a partition of a program repeatedly a given number of times or a certain condition is satisfied.

Ø When the condition becomes false then the loop will be end and control goes out from the control loop.

Ø It is used for executing repeatedly of any statement.

Ø There are two types of loop such as-

1. Entry control loop.

2. Exit control loop.

1. Entry control loop:- in this loop condition is checked first then execute the statement body of the loop.

Ø There are two entry control loop such as-

1. for loop

2. while loop

Exit control loop:- in this loop execution of statement is first then check the condition.

Ø There is one exit control loop –

1. Do- while loop.

for loop:- this lop is the easiest loop among all the loop in ‘c++’.

Ø It contains all the loop control statements in one place in a pair of parenthesis.

Ø Which make it more clear and understandable.

Ø This loop is used for fixing iteration.

Ø This loop comes in the category of the entry control loop and unconditional loop.

Ø It contains initialization, test condition and increment /decrement.

Ø The control checks the initialization first and then check the condition and executes the body of the loop if the test condition is satisfied.

Ø Again control goes to increment/ decrement and then again check the condition.

Ø If the test condition is satisfied then again the body of the loop is executed this process continuously until the test condition becomes false.

Ø If the test condition is not satisfied then control exits from the loop.

Syntax :- for(initialization ; test condition ; increment/decrement)

{

Statement;

}

Flow chart:-

#include<iostream.h>

#include<conio.h>

void main()

{

clrscr();

int i;

for(i=1; i<=5; i++)

{

Cout<<”VMSM programming classes by vikas mishra\n”;

}

getch();

}

OUTPUT

VMSM programming classes by vikas mishra

#include<iostream.h>

#include<coniio.h>

void main()

{

clrscr();

int n, i, r1=-1 , r2=1, r3;

cout<<”enter any number=”;

cin>>n;

for(i=1;i<=n;i++)

{

r3=r1+r2;

cout<<”\t”<<r3;

r1=r2;

r2=r3;

}

getch();

}

While loop:- this loop comes in the category of entry control loop or conditional loop.

· This loop executes its body of statements repeatedly as long as a specified condition is true.

· In this loop test condition is evaluated first, if the test condition is true then the body of the loop will be executed.

· In this loop after execution again test condition is evaluated and if found true then the body of the loop is executed again. this process continues until the condition becomes false.

· When the specified condition becomes false then control is the exit from the loop.

Syntax:- while ( test condition)

{

Body of the loop

}

Q. write a program to print your name five times by using while loop.

#include<iostream.h>

#include<conio.h>

void main()

{

clrscr();

int i=1;

while(i<=5)

{

cout<<”vikas mishra”<<”\n”;

i++;

}

getch();

}

Output

Vikas mishra

DO-while loop:- This loop comes in the category of exit control loop and conditional loop.

Ø This loop executes its body of statement at least once whether the specified condition is true or false.

Ø It executes its body of statement first then evaluates the test condition. If the test condition is satisfied then it again executes its body. This process continues until the test condition becomes false.

Ø When the test condition is not satisfied then go-out from the loop and the loop end.

Ø Syntax:-

{

Statement;

Increment /decrement;

}

While (test condition);

Flow chart:-

Q. write a program to print your name five times by using do-while loop.

#include<iostreamh>

#include<conio.h>

void main()

{

int i=1;

clrscr();

{

cout<<”vikas mishra\n “;

i++;

}

while(i<=5);

getch();

}

OUTPUT

Vikas mishra

Nested loop:- one loop within another loop is called nested loop.

Syntax :-

for( initialization; test condition; increment / decrement)

{

for( initialization; test condition; increment/ decrement)

{

Statement;

}

Q. write a program to print the following format.

****

#include<iostream.h>

#include<conio.h>

void main()

{

clrscr();

int i , j;

for(i=1;i<=4; i++)

{

for( j=1;j<=4;j++)

{

cout<<”*”;

}

cout<<”\n”;

}

getch();

}

OUTPUT

****

FUNCTION:- The number of statements grouped in a logical unit to perform some specific task is called function.

Ø Function makes the program easier to understand and maintain.

Ø A large program is broken down into small functions. i.e. A large program is made from variables small function.

Ø Error detection and correction are easy when we use the function in a program.

Ø It also provides code reusability facility.

There are two types of function such as –

1. Library /built in / predefined functions

2. User –define function

1. Library function:-predefined function are called library function. We can use library function by including the respective header file.

Ø We can not understand the internal structure of library function.

Ø We can not modify of this function.

Ø E.g.- sqrt() , pow(), ...etc.

2. User-define function :- The function defined by the user is called user defined function.

Ø We can understand the internal working structure of user define function.

Ø We can modify user-defined function.

Ø There is no need to include any header file.

Parts of function :-

1. Function prototype:- it determines the name of function and number of argument and their type and also returns type.

Ø It is generally located at the top of the program.

2. Function calling:- when we want to execute the statement of the function then we call function. It contains the actual argument.

3. Function definition:- it contains the various statements which to be executed after calling.

Ø Generally it is located outside of the main function.

Ø It contains formal arguments.

4. Actual argument:- Argument written in function calls is called an actual argument.

5. Formal argument :- Arguments written in function definition is known as a formal argument.

6. Return state:- it sends the value to the calling function.

Ø User -define function can be used in three ways –

i. No argument no return type.

ii. With argument but not return type.

iii.With argument with the return type.

Syntax:-

int sum(int x, int y )

{

int z=x+y

return z;

}

void main()

{

clrscr();

sum(a,b);

getch();

}

Passing argument in function in three ways such as-

1. Call by value /pass by value

2. Call by address/pass by address

3. Call by reference/pass by reference

| Call by value / pass by value:- in this technique, value is passed in the function argument.

Ø In this technique actual argument is copied to the formal argument and all operations are performed on the formal argument.

Ø Any change made an informal argument then does not nay an effect on the actual argument.

E.g.- write a program to represent call by value/pass by value.

| Call by reference /pass by reference:-in this technique memory address is passed to function argument.

Ø In this technique address is implicitly passed to formal arguments.

Ø Any changes made informal arguments affect the actual argument. i.e. changes are made permanent.

Ø E.g.:- write a program to represent the swapping by using call by reference.

| Call by address/pass by address:-in this technique memory address is passed to function arguments.

Ø In this technique address explicitly passed to the formal arguments.

Ø Any changes made informal arguments effects in actual arguments. i.e. change is made permanent.

Ø E.g.- write a program to represent the swapping by using a call by address.

Function overloading:- it means that multiple functions in a class having the same name with different arguments for different purposes.

It is an example of polymorphism.

It is an important feature of object oriented programming.

Example :-

#include<iostream.h>

#include<conio.h>

public class num

{

int r,l,b,h;

void area(int);

void area(int , int);

void area(int ,int,int);

};

void num::area(int r)

{

cout<<”enter value of r=”;

cin>>r;

cout<<”Area of circle=”<<3.14*r*r;

}

void num::area(int l,int b)

{

cout<<”Enter the value of l and b=”;

cin>>l>>b;

cout<<”Area of rectangle=”<<(l*b);

}

void num::area(int l, int b, int h)

{

cout<<”Enter the value of l,b,h=”;

cin>>l>>b>>h;

cout<<”volume of the cuboids=”<<(l*b*h);

}

void main()

{

clrscr();

num obj;

obj1.area();

obj2.area();

obj3.area();

getch();

}

Output

Enter the value of r=2

Area of circle=12.56

Enter the value of l and b=2

Area of rectangle=6

Enter value of l,b,h=2

The volume of cuboids= 24

Friend class:- A class which is declared with friend keyword and private data member of another class is known as a friend class.

It is possible to declare one or more friend class.

Example:-

class vmsm

{

private :

int a, b;

friend class pro;

};

Constructor:- it is a special member function that is used to initialize data member.

Ø It is different from all other member function because it has the same name as its class name and automatically invoked by the compiler when the object is created.

Ø It is similar to other member functions. i.e. it can be defined inside or outside of the class and also be passed parameter or argument.

There are following characteristics of constructor such as-

Ø Constructor has the same name as its class name.

Ø A constructor should be declared in the public section.

Ø Constructor is used to initializing the data member of the class.

Ø Constructor does not return any type not even void.

Ø Constructor calls automatically when the object is created.

Ø Constructor can be overloaded i.e. multiple constructors can be used in a single class.

Ø A constructor is not declared in the class then the default constructor is generated by the compiler.

Ø Constructor follows all the access rules which are followed by another member function of class.

Ø It can be parameterized like other member function.

Ø Constructor can not be virtual or cant is inherited.

Types of constructor:

There are three types of constructor such as-

1. Default constructor

2. Parameterized constructor

3. Copy constructor

1 Default constructor:- A constructor without a parameter or argument is known as the default constructor.

Syntax :-

Class class_name

{

public:

class_name()

{

Statement;

}

};

Example :-

#include<iostream.h>

#include<conio.h>

class Vmsm

{

private:

int num1 , num2;

public:

Vmsm()

{

num1=20;

num2=40;

}

void show()

{

cout<<”num1=”<<num1;

cout<<”num2=”<<num2;

}

};

int main()

{

Vmsm obj;

obj.show();

return 0;

getch();

}

Output

num1=20

num2=40

Parameterized constructor:- A constructor which is declared with parameter is known as parameterized constructor.

It may be single or multiple.

Syntax:-

Class class_name

{

public:

int a,b;

Class_name(int x, int y)

{

Statement;

}

};

Example :-

#include<iostream.h>

#include<conio.h>

class VMSM

{

private:

int b,c;

public:

VMSM(int b1, int c1)

{

b=b1;

c=c1;

}

int getX()

{

return b;

}

int getY()

{

return c;

}

};

int main()

{

VMSM ob(30,40);

cout<<”value=”<< ob.getX()<<”value=”<<ob.getY();

return 0;

getch();

}

Output

Value=30 value=40

Copy constructor:- it is a type of constructor which is used to copy the value of one object to another object of the some class.

Syntax:

Class class_name

{

Access modifier:

Class _name(const class_name &ob)

{

Statement;

}

};

Example :-

#include<iostream.h>

#include<conio.h>

class vmsm

{

public:

int x;

vmsm(int a)

{

x=a;

}

vmsm(vmsm &ob)

{

x=ob.x;

}

};

int main()

{

vmsm a1(30);

vmsm a2(a1);

cout<<a2.x;

return 0;

getch();

}

Output

Constructor overloading:- it means multiple constructors in a class with different argument for a different purpose.

Example :-

#include<iostream.h>

#include<conio.h>

class vmsm

{

public:

float area;

vmsm()

{

area=0;

}

vmsm(int a, int b)

{

area= a*b;

}

void show()

{

cout<<area;

}

};

int main()

{

vmsm ob;

vmsm obj(10, 30);

ob.show();

obj.show();

return 1;

getch();

}

Output

300

Destructor:- A destructor is a special member function of a class that automatically executed when an object is destroyed.

It has the same name as its class name but proceeded with ~ symbol.

It is used to destroy the object that has been created.

It never takes any argument and does not return value i.e. destructor is used to deallocate memory space or cleaning the operation or task performed by an object.

It can not be overloaded.

Destructor follows all the access rules as are followed by the other member function.

When no destructor is in the class then compiler invokes automatically default destructor.

Example:-

vmsm obj;

ob.vmsm::~vmsm();

program :-

#include<iostream.h>

#include<conio.h>

class vmsm

{

private:

int n1, n2;

public ;

vmsm(int x, int y)

{

cout<<”inside constructor”<<”\n”;

n1=x;

n2=y;

}

void show()

{

cout<<”n1=”<<n1<<”\n”;

cout<<”n2=”<<n2<<”\n”;

}

~vmsm()

{

cout<<”inside destructor”;

}

};

int main()

{

vmsm obj1(10,30);

obj1.show();

obj1.vmsm::~vmsm();

getch();

return 0;

}

Output

Inside constructor

n1=10;

n2=30;

inside destructor

Inheritance:- it is the most important feature of object-oriented programming.

It is the method or technique by which objects of one class gets the properties of objects of another class.

It is a way of creating of a new class from the existing class.

It provides the facility of code reusability. i.e. redundant code can be removed.

It enables to derive a new class which is known as derive /child/descendent/subclass from the existing class which is known as base/parent /ancestor /superclass.

Derive class:-it can access a member of the base class according to the rule of inheritance. But the base class can not access a member of derived class.

Base class:- A class which allows accessing data members and member function to a derived class is called a base class.

Derived class:- A class that access or inherit the properties of the base class is called derive class.

Derive the class automatically access the data member and member function without rewriting them again. A derive class may also be a base class of other derived class.

There are following rules for inheritance such as-

👉base class can be inherited in three ways or mode.

1. public

2. private

3. protected

1. Public mode:- when base class is inherited with public mode then the public member of the base class become a public member of derived class.

2. Protected mode:- when the base class is inherited with protected mode then the protected member of base class becomes protected member of derived class.

3. Private mode:- when the base class is inherited with private mode then the private members of base class become a private member of the derived class.

Syntax :- class derived _ class name : mode /access specifier base_class

{

Stmt ;

};

Example :-

class vmsm

{

public:

int a,b,c;

};

class vm: public vmsm

{

Statement;

};

Write a program to enter time in seconds. And then display after converting them into hours, minutes, and seconds.

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