The document discusses the origins and features of the C++ programming language. It began as an expanded version of C created by Bjarne Stroustrup in 1979. Key features discussed include input/output using cout and cin operators, manipulators like endl and setw for formatting output, reference variables which provide an alias for another variable, and the different data types in C++ including built-in types like int and char, and derived types like arrays, functions, pointers, references, structures, unions, classes, and enumerations.

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Haresh Jaiswal
Rising Technologies, Jalna.

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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 Bjarne
Stroustrup 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, it
has its limits. In C, once a program exceeds from 25,000
to 100,000 lines of code, it becomes so complex that it is
difficult 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, the
invention of C++ was necessitated by one major
programming factor: increasing complexity.
 The essence of C++ is to allow the programmer to
manage 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 on
the 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 in
myVariable

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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 used
manipulators 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 as
using the newline ‘n’ in ‘C’.
cout << “Rising Technologies” << endl;

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Manipulators
int 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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Manipulators
A = 2314
B = 28
C = 327
 But above form is not ideal, it should rather appear like
this,
A = 2314
B = 28
C = 327
 Here output is right aligned.

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Manipulators
A = 2314
B = 28
C = 327
 Above form of output is possible only if we specify a
common field width for all the numbers and force them
to 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 for
printing the value of myVariable, this value is right
justified within the field.
3 7 2

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Manipulators
setprecision(argument);
 The setprecision manipulator sets the floating-point
precision 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 same
memory 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/alternate
name 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 and
then 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
Array
Function
Pointer
Reference
User defined
Types
Structure
Union
Class
Enumeration
Built In Types
Empty Type Floating TypesIntegral Types
Int char float double
C++ Data Types
void