Introduction to c++

Introduction to C++
BY HIMANSHU KAUSHIK

What is c++ ?
 C++ is a object-oriented language
 It is the “successor” to C, a procedural language
 (the “++” is called the successor operator in C++)
 C was derived from a language called B which was in turn derived from
BCPL
 C was developed in the 1970’s by Dennis Ritchie of AT&T Bell Labs
 C++ was developed in the early 1980’s by Bjarne Stroustrup of AT&T Bell
Labs.
 Most of C is a subset of C++

People & Programs
 User: an individual who runs, or executes,
a program
 Programmer: an individual who creates, or
writes, a program

C++ Programming
 Consists of…
Declarations
 Define the use of various identifiers, thus creating the elements used by the
program (computer)
Statements
 Or executable statements, representing actions the computer will take on
the user’s behalf

Identifiers
 Names for various entities used in a program;
used for...
 Variables: values that can change frequently
 Constants: values that never changes
 Functions: programming units that represents
complex operations
 Parameters: values that change infrequently

A Simple c++ Program
#include <iostream.h>
int main()
{
// Declarations
// Statements
return 0;
}

The Header File
int main()
{
// Declarations
// Statements
return 0;
}
 Compiler directive:
Tells the compiler
what to do before
compiling
 This one includes
source code from
another file

The Main Statement
int main()
{
// Declarations
// Statements
return 0;
}
 Header for main function
States…
 data type for the return
value
 identifier for function
 list of arguments between
parenthesis
(none for this function)

The Braces
int main()
{
// Declarations
// Statements
return 0;
}
Braces enclose the body of
the function
They represent the start and
end of the function

The Declaration Statement
int main()
{
// Declarations
// Statements
return 0;
}
 Declarations and
statements
 Main body of function
(or main part)
 “//” represents the start
of a comment

The return Statement
int main()
{
// Declarations
// Statements
return 0;
}
 Return statement
 specifies the value
the function returns
 All (almost)
declarations and
statements end with
a semi-colon “;”

Sample C++ Program
void main()
{
int number;
cout << “Enter a number” << endl;
cin >> number;
cout << “You entered: “ << number << endl;
}
What is the Output of this Program?

The DataTypes
void main()
{
int number;
cin >> number;
}
 Variable declaration
 The identifier number is
declared as being of
data type int, or integer

The Count ?
void main()
{
int number;
cin >> number;
}
 cout
the output statement for C++
 Note the direction of “<<“
 endl represents an end-of-line

Cin ?
void main()
{
int number;
cin >> number;
}
cin
the input statement for C++
Note the direction of “>>”

Copy That Down
void main()
{
int number;
cin >> number;
}

Value Assignment In c++
 Assignment is an operation that assigns
the value of an expression to a variable
 Ex. Total = 2 + 3 + 5
 First, the expresssion “2 + 3 + 5” is
evaluated
 Then, this value is assigned to the variable
“Total”

Assignment
 When a variable is declared, space is
allocated in the computer’s memory for
the variable
 Each data type requires a different
number of bytes in memory for storing a
variable
 int - 2
float - 4
double - 8
char, bool - 1

Arithmetic Operations
Addition: 2 + 3
Subtraction: 5 - 2
Multiplication: 10 * 4
Division: 12 / 3

I Have A problem for you
Problem: To determine the average of three
numbers
Task: Request, from the user, three numbers,
compute the average and the three numbers,
and print out the original values and the
computed average
Do it!
You have 20 minutes!

Introduction to c++

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