01. introduction to C++

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

Haresh Jaiswal

Rising Technologies, Jalna.


Agenda Introduction

Input/Output

Manipulators

Reference Variables

C++ Data Types


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++”


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.


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.


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.


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)


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.


Input/Output in C++

cout << “Hello…”

VariableInsertion operator

Object

Hello…


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

cin >> myVariable;

Will receive input from keyboard and store it inmyVariable


Input/Output in C++

cin >> 45.6

Object

Extraction Operator

myVariable


Manipulators Manipulators are operators that are used to format the

output data display. The most commonly usedmanipulators are…

endl

setw

setprecision


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;


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


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.


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.


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


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


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


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


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.


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


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

01. introduction to C++

Education

origin of c c

c rising technologies

jalna mh

c cout

c cin

c program

c extensions

theinvention of c