Rising Technologies, Jalna (MH). + 91 9423156065, http://www.RisingTechnologies.in 1

Haresh Jaiswal

Rising Technologies, Jalna.

Rising Technologies, Jalna (MH). + 91 9423156065, http://www.RisingTechnologies.in 2

Agenda Introduction

Input/Output

Manipulators

Reference Variables

C++ Data Types

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Origin of C++ C++ began as an expanded version of C.

The C++ extensions were first invented by BjarneStroustrup in 1979 at Bell Laboratories.

Initially called the new language "C with Classes”

Later in 1983 the name was changed to “C++”

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Origin of C++ Over the years, computer programs have become larger

and more complex.

Even though C is an excellent programming language, ithas its limits. In C, once a program exceeds from 25,000to 100,000 lines of code, it becomes so complex that it isdifficult to grasp as a totality.

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Origin of C++ Although C was one of the most liked and widely used

professional programming languages in the world, theinvention of C++ was necessitated by one majorprogramming factor: increasing complexity.

The essence of C++ is to allow the programmer tomanage larger, more complex programs.

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Input/Output in C++ The most common way in which a program

communicates with the outside world is through simple,character oriented Input/Output (IO) operations.

C++ provides two useful operators for this purpose:

>> for input and

<< for output.

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Input/Output in C++ Every C++ Program must include the header ‘iostream.h’

It contains declarations for the stream objects

cout & cin

stream insertion & stream extraction operators.

<< (Stream insertion)

>> (Stream Extraction)

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Input/Output in C++ An Example of console output using cout & << operator

cout << “Hello”;

Causes the string in quotation mark to be displayed onthe screen/console.

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Input/Output in C++

cout << “Hello…”

VariableInsertion operator

Object

Hello…

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Input/Output in C++ An Example of console input using cin & >> operator.

cin >> myVariable;

Will receive input from keyboard and store it inmyVariable

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Input/Output in C++

cin >> 45.6

Object

Extraction Operator

myVariable

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Manipulators Manipulators are operators that are used to format the

output data display. The most commonly usedmanipulators are…

endl

setw

setprecision

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Manipulators The endl manipulator, when used in an output statement,

causes a line feed to be inserted. It has the same effect asusing the newline ‘\n’ in ‘C’.

cout << “Rising Technologies” << endl;

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Manipulatorsint a = 2314, b = 28, c = 327;

cout << “A = ” << a << endl;

cout << “B = “ << b << endl;

cout << “C = “ << c << endl;

Above code will print 3 lines of output as follows

A = 2314

B = 28

C = 327

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ManipulatorsA = 2314

B = 28

C = 327

But above form is not ideal, it should rather appear likethis,

A = 2314

B = 28

C = 327

Here output is right aligned.

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ManipulatorsA = 2314

B = 28

C = 327

Above form of output is possible only if we specify acommon field width for all the numbers and force themto print right aligned.

setw manipulator can do this job.

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Manipulators

int myVariable = 372;

cout << setw(5) << myVariable;

The manipulator setw(5) specifies a field width 5 forprinting the value of myVariable, this value is rightjustified within the field.

3 7 2

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Manipulators

setprecision(argument);

The setprecision manipulator sets the floating-pointprecision to the specified argument.

float myVariable = 1.123456;

cout << setprecision(2) << myVariable;

Will print following output

1.12

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Reference Variable. A ‘Reference Variable’ provides an Alias (Alternate Name)

for a previously defined variable.

int a = 10;

int &r = a;

// in above statement „r‟ is declared as

reference to „a‟, hence

r++;

Will increase both ‘a’ & ‘r’ by 1

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Reference Variable.

int &r = a;

After this declaration ‘a’ and ‘r’ both refer to the samememory location, as if they were the same variable.

int a = 10;

10

Variable in memory

int &r = a;

One location two names

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Reference Variable. Notice that a reference does not create a copy of an

object/variable, it simply provides an alias/alternatename for it, Hence after following declaration…

int &r = a;

Both ‘a’ and ‘r’ will refer to same memory location.

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Reference Variable. A Reference must be initialized when it is declared, it

must be an alias for something upon declaration.

It would be illegal to declare a reference variable andthen initialize it later.

int a;

int &r; // illegal : reference without initializer

r = a;

int a;

int &r = a; // legal

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C++ Data Types

Derived Types

ArrayFunctionPointerReference

User defined Types

StructureUnionClassEnumeration

Built In Types

Empty Type Floating TypesIntegral Types

Int char float double

C++ Data Types

void