C++ is an object oriented programming language.

C++ is an extension of C with a major addition of the class construct feature.

C++ is superset of C. Features like classes, inheritance, function

overloading, and operator overloading make C++ a truly object-oriented language.

OO features in C++ allow programmers to build large programs with clarity, extensibility and ease of maintenance, incorporating the spirit and efficiency of C.

/* Simple hello world program*/# include <iostream>// This is include directiveusing namespace std;int main(){cout << “Hello World!”; //C++ statementreturn 0;

}

Average of numbers.◦ It will take two numbers from the console and

print the average of the two numbers.

Keywords Identifiers Constants Strings Operators

Keywords Identifiers Constants Strings Operators

Some words are reserved for implementing the specific C++ language features.

asm, auto, bool, break, case, catch, char, class, const, const_cast, continue, default, delete, do, double, dynamic_cast, else, enum, explicit, export, extern, false, float, for, friend, goto, if, inline, int, long, mutable, namespace, new, operator, private, protected, public, register, reinterpret_cast, return, short, signed, sizeof, static, static_cast, struct, switch, template, this, throw, true, try, typedef, typeid, typename, union, unsigned, using, virtual, void, volatile, wchar_t, while

Keywords Identifiers Constants Strings Operators

Identifiers refer to the names of variables, functions, arrays, classes , etc. created by the programmer.

Rules for creating it.◦ Only alphabet characters, digits and underscore

are permitted.◦ The name cannot start with digit.◦ Uppercase and lowercase letters are distinct.◦ A declared keyword cannot be used as a variable.

Type Bytes Range

char 1 -128 to 127signed: -128 to 127unsigned: 0 to 255

short int 2 -31768 to 32767signed: -32768 to 32767unsigned: 0 to 65535

int 2 -32768 to 32767signed: -31768 to 32767unsigned: 0 to 65535

long int 4 -2147483648 to 2147483647signed: -2147483648 to 2147483647unsigned: 0 to 4294967295

float 4 3.4E-38 to 3.4E+38

double 8 1.7E-308 to 1.7E+308

long double 10 3.4E-4932 to 1.1E+4932

This program will take different values from console and perform various mathematical operation on these values and print the result to the console.

Structures and Classes◦ Basis for OOP.◦ Classes enable to combine data and procedures.

Enumerated Data Type◦ It provides a way to attaching names to the

numbers◦ Increase comprehensibility of the code.◦ Alternative mean for creating symbolic constants◦ Enumerates a list of words by assigning them

values 0,1,2 and so on.enum shape {circle, square, triangle};enum colour {red, blue=4, green=8};

Arrays◦ Values of similar type stored in continuous

memory locations.◦ int a[10]; char string[3]=“xyz”;

Functions◦ Set of statements to perform specific tasks

Pointers◦ Special variables to store the memory location of

other variables.◦ Used in referencing memory.◦ Concept of constant pointer introduced in c++.

Keywords Identifiers Constants Strings Operators

Refer to fixed values that do not change in thw execution of the program.◦ 123 //decimal integer◦ 12.34 //floating point integer◦ 037 //octal integer◦ 0x2 //Hexa decimal◦ “C++” //string constant◦ ‘A’ //character constant◦ L’ab’ //wide-character constant

Using the qualifier const◦ const float pi = 3.14;

Using enum◦ enum{x,y,z};◦ enum{x=200,y=300,z=400};◦ enum{off,on};

Keywords Identifiers Constants Strings Operators

Variables that can store non-numerical values that are longer than one single character are known as strings.

The C++ language library provides support for strings through the standard string class.

// my first string#include <iostream>#include <string>using namespace std;int main (){string mystring = "This is a string";cout << mystring;return 0;}

Keywords Identifiers Constants Strings Operators

> greater than 5 > 4 is TRUE < less than 4 < 5 is TRUE >= greater than or equal 4 >= 4 is

TRUE <= less than or equal 3 <= 4 is TRUE == equal to 5 == 5 is TRUE != not equal to 5 != 4 is TRUE

Basic If Statement Syntax

The structure of an if statement is as follows: if ( TRUE ) Execute the next statement Here is a simple example that shows the

syntax: if ( 5 < 10 ) cout<<"Five is now less than ten, that's a

big surprise";

Sometimes when the condition in an if statement evaluates to false, it would be nice to execute some code instead of the code executed when the statement evaluates to true. The "else" statement effectively says that whatever code after it (whether a single line or code between brackets) is executed if the if statement is FALSE.

It can look like this:if ( TRUE ) { // Execute these statements if TRUE}else { // Execute these statements if FALSE}

#include <iostream>

using namespace std;

int main() // Most important part of the program!{ int age; // Need a variable... cout<<"Please input your age: "; // Asks for age cin>> age; // The input is put in age cin.ignore(); // Throw away enter if ( age < 100 ) { // If the age is less than 100 cout<<"You are pretty young!\n"; // Just to show you it works... } else if ( age == 100 ) { // I use else just to show an example cout<<"You are old\n"; // Just to show you it works... } else { cout<<"You are really old\n"; // Executed if no other statement is } cin.get(); // equal return 0;}

Another use of else is when there are multiple conditional statements that may all evaluate to true, yet you want only one if statement's body to execute. You can use an "else if" statement following an if statement and its body; that way, if the first statement is true, the "else if" will be ignored, but if the if statement is false, it will then check the condition for the else if statement. If the if statement was true the else statement will not be checked. It is possible to use numerous else if statements to ensure that only one block of code is executed.

if ( <condition> ) { // Execute these statements if <condition> is TRUE}else if ( <another condition> ) { // Execute these statements if <another condition> is TRUE and // <condition> is FALSE}

#include <iostream>

using namespace std; // So we can see cout and endl

int main(){ int x = 0; // Don't forget to declare variables while ( x < 10 ) { // While x is less than 10 cout<< x <<endl; x++; // Update x so the condition can be met

eventually } system ("pause"); cin.get();}

DO..WHILE - DO..WHILE loops are useful for things that want to loop at least once.

The structure isdo { } while ( condition );

#include <iostream>

using namespace std;

int main(){ int x;

x = 0; do { // "Hello, world!" is printed at least one time // even though the condition is false cout<<"Hello, world!\n"; } while ( x != 0 ); cin.get(); }

Constant expressions Integral expressions Float expressions Pointer expressions Relational expressions Logical expressions Bitwise expressions

The if statement

Simple if statement if…..else statement

if(expression){

statement 1;}statement 2;statement 3;

if(expression){

statement 1;}else{ statement 2;}statement 3;

The switch statement

switch(expression){

case 1:statement1;

break|continue;case 2:statement2;

continue|break; . . .

default:statement3;

}statement4;

The do-while statement

do{ statement1;}while(condition);statement2;

The while statement

while(condition){ statement1;}statement2;

The for statement

for (intialization;condition;increment){ statement1;}statement2;

A piece of code that perform specific task. Introduces modularity in the code. Reduces the size of program. C++ has added many new features to the

functions to make them more reliable and flexible.

It can be overloaded.

Function declaration◦ return-type function-name (argument-list);◦void show();◦float volume(int x,float y,float z);

Function definitionreturn-type function-name(argument-list){statement1;statement2;

} Function call

◦ function-name(argument-list);◦ volume(a,b,c);

The main function Returns a value of type int to the operating

system.

int main(){………………return(0);}

This program will take the values of length, breadth and height and prints the volume of the cube. It uses the function to calculate it.

Parameter Passing◦ Pass by value◦ Pass by reference

Reference variable Pointersvoid swap (int &a, int &b){ int t=a; a=b; b=t;}

void swap(int *a, int *b){ int t; t=*a; *a=*b; *b=t;}

swap(m,n); swap(&m,&n);

Parameter passing◦ Return by reference

int & max (int &x, int &x){ if(x>y) return x; else return y;}

max(a,b)=-1;

C++ allows to use the same function name to create functions that perform a variety of different tasks.

This is know as function polymorphism in OOP.

int add (int a, int b); //prototype 1int add (int a, int b, int c); //prototype 2double add (double x, double y);//prototype 3double add (int p, double q);//prototype 4double add (double p, int q); //prototype 5

add(5,10);//uses prototype 1add(15,10.0);//uses prototype 4add(12.5,7.5); //uses prototype 3add(5,10,15); //uses prototype 2add(0.75,5); //uses prototype5

Structures Revisited◦ Makes convenient to handle a group of logically

related data items.struct student //declaration{ char name[20]; int roll_number; float total_marks;};struct student A;// C declarationstudent A; //C++ declarationA.roll_number=999;A.total_marks=595.5;Final_Total=A.total_marks + 5;

Limitations◦ C doesn’t allow it to be treated like built-in data

types.struct complex{float x; float y;};struct complex c1,c2,c3;c3=c1+c2;//Illegal in C◦ They do not permit data hiding.

Can hold variables and functions as members.

Can also declare some of its members as ‘private’.

C++ introduces another user-defined type known as ‘class’ to incorporate all these extensions.

Class is a way to bind the data and procedures that operates on data.

Class declaration:class class_name{

private:variable declarations;//classfunction declarations;//members

public:variable declarations;//classfunction declarations;//members

};//Terminates with a semicolon

Class members that have been declared as private can be accessed only from within the class.

Public class members can be accessed from outside the class also.

Supports data-hiding and data encapsulation features of OOP.

Objects are run time instance of a class. Class is a representation of the object, and

Object is the actual run time entity which holds data and function that has been defined in the class.

Object declaration:class_name obj1;class_name obj2,obj3;class class_name{……}obj1,obj2,obj3;

Accessing class members◦ Object-name.function-name(actual-arguments);◦ obj1.setdata(100,34.4);

Defining Member Functions◦ Outside the class definition.return-type class-name::function-name (argument declaration)

{Function body;

}◦ Inside the class definition.Same as normal function declaration.

Object as arraysclass employee{char name [30];float age;public:void getdata(void);void putdata(void);

};

employee manager[3];//array of manageremployee worker[75];//array of worker

Manager[i].putdata();

This program will create an array, takes the values for each of the element and displays it.

An object may be used as a function arguments.

This program creates a ‘time’ class in hour and minute format. There is a function called ‘sum’ performs the addition of time of two object and assign it to the object that has called the function.

Friend function are used in the situation where two classes want to share a common function.

Scientist and manager classes want to share the function incometax().

C++ allows the common function to be made friendly with both the classes, thereby allowing the access to the private data of these classes. This function need not to be the member function of any of these classes.

It is not in the scope of the class, hence it cannot be called using the object of any class. It can be invoked normally.

It cannot access member names directly, but with the help of an object. Eg obj1.x

It can be declare either in the public or the private part of a class without affecting its meaning.

Usually, it has the objects as arguments.

This program declares a function ‘max’ as friend to two classes and demonstrate how to use them.

In order to behave like built-in data types, the derived-data types such as ‘objects’ should automatically initialize when created and destroys when goes out of scope.

For this reason C++ introduces a special member functions called constructor and destructor to automatically initialize and destroy the objects.

Name is same as that of class. Invoked when ever an object of its

associated class is created.

class integer{

int m,n;public:integer(void);….….

};integer :: integer(void){ m=0;n=0;}

Declared in the public section. Invoked automatically when the objects are

created. Do not have return type. Cannot be inherited. Though a derived class can

call the base class constructor. Can have default arguments. Cannot be virtual. We cannot refer to their addresses. An object with a constructor (or destructor)

cannot be used as a member of a union. They make ‘implicit calls’ to the operators ‘new’

and ‘delete’ when memory allocation is required.

Parameterized Constructors

class integer{

int m,n;public:integer(int x, int y);….….

};integer :: integer(int x,int y){ m=x;n=y;}

integer num1 = integer(0,100);//explicit callint num1(0,100);//implicit call

Multiple Constructors

class integer{

int m,n;public:integer(void);

integer(int x, int y);….….

};integer :: integer(void){ m=0;n=0;}integer :: integer(int x,int y){ m=x;n=y;}

Program demonstrate the use of constructors.

Dynamic initialization of Objectscin>> real>>imag;Obj1=complex(real,imag);

Copy Constructor.class integer{

int m,n;public:integer(integer &i){m=i.m;n=i.n;};….

};

integer num1(num2);

Is used to destroy the objects that have been created.~complex(){}

Never takes any arguments nor does return any value.

C++ tries to make the user-defined data types behave in much the same way as the built-in data types.

In built-in data types we have:◦ c=a+b//a,b and c are of type ‘int’.

We can also have in C++:◦ object1=object2+object3;

C++ has the ability to provide the operators with a special meaning for a data type. This mechanism is known as operator overloading.

return-type class-name::operator op (arglist)

Operator functions must be either member functions or friend functions.◦ vector operator+(vector);◦ vector operator-();◦ friend vector operator+(vector,vector);◦ friend vector operator-(vector);◦ int operator==(vector);◦ friend int operator==(vector,vector);

friend void operator-(space &s);

void operator-(space &s){ s.x=-s.x; s.y=-s.y;s.x=-s.z;

}

a, b and c are objects of class ‘complex’ c=a.sum(b);//functional notation, function ‘sum’ is member function.

c=sum(a,b);//functional notation, function ‘sum’ is friend function.

c=a+b; // arithmetic notation, can be defined in both the ways (member function and friend function).

Using member functionscomplex complex::operator+(complex c){ complex temp; temp.x=x+c.x; temp.y=y+c.y; return(temp);}

Using friend function.friend complex operator+(complex, complex); //declaration

complex operator+(complex a, complex b){return complex ((a.x+b.x),(a.y+b.y));}//defination

C++ strongly support the concept of reusability.

C++ classes can be reused in several ways. Creating new classes by reusing the

properties of existing once. The reuse of a class that has already been

tested, debugged and used many times can save us the effort of developing and testing the same again.

Mechanism is Inheritance. Base class ---Derived class

class derived-class-name : visibility-mode base-class-name

{………};

Visibility mode is optional.(by default: private)

Visibility mode specifies whether the features of the base class are privately derived or publicly derived.

d.get_ab();d.get_a();d.show();Will not work.void mul() void display(){ { get_ab(); show_a(); c=b*get_a(); cout<<“b=“<<b<<“\n”} <<“c=”<<“\n\n”;

}

Inside the class.class alpha{private://optional…………//visible inside this class onlyprotected://visible inside this class …………//and its immediate derived class

public://visible to all …………};

Multilevel Inheritanceclass A{…};Class B : public A{…};Class C : public B{…}; Multiple Inheritanceclass P : public M, public N{…};