Here is a potential solution to the problem in C++: #include <iostream> using namespace std; int main() { int num1, num2, num3; cout << "Enter three numbers: "; cin >> num1 >> num2 >> num3; int total = num1 + num2 + num3; float average = total / 3.0; cout << "The numbers entered were: " << num1 << ", " << num2 << ", " << num3 << endl; cout << "Their average is: " << average; return 0; } Some key points: - Use cin to input the 3 numbers from the

1. Introduction to C++
BY HIMANSHU KAUSHIK

2. 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++

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

4. 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

5. 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

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

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

8. The Main Statement
#include <iostream.h>
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)

9. The Braces
#include <iostream.h>
int main()
{
// Declarations
// Statements
return 0;
}
Braces enclose the body of
the function
They represent the start and
end of the function

10. The Declaration Statement
#include <iostream.h>
int main()
{
// Declarations
// Statements
return 0;
}
 Declarations and
statements
 Main body of function
(or main part)
 “//” represents the start
of a comment

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

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

13. The DataTypes
#include <iostream.h>
void main()
{
int number;
cout << “Enter a number” << endl;
cin >> number;
cout << “You entered: “ << number << endl;
}
 Variable declaration
 The identifier number is
declared as being of
data type int, or integer

15. The Count ?
#include <iostream.h>
void main()
{
int number;
cout << “Enter a number” << endl;
cin >> number;
cout << “You entered: “ << number << endl;
}
 cout
the output statement for C++
 Note the direction of “<<“
 endl represents an end-of-line

16. Cin ?
#include <iostream.h>
void main()
{
int number;
cout << “Enter a number” << endl;
cin >> number;
cout << “You entered: “ << number << endl;
}
cin
the input statement for C++
Note the direction of “>>”

17. Copy That Down
#include <iostream.h>
void main()
{
int number;
cout << “Enter a number” << endl;
cin >> number;
cout << “You entered: “ << number << endl;
}

18. 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”

19. 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

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

21. 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!

22. Any Queries ?