4 CP 9 / 4 IT 7 – OOP Lab
C++ Programs
1.
Programs
Inheritance
2.
Programs
of Operator Overloading (Complex Number Arithmetic, Polar Coordinates)
3.
Programs
using Friend Functions
4.
Various
Matrices Operation
5.
Stack
Operations using OOPs Concepts
6.
To
Implement Tower of Hanoi Problem
LAB MANUAL
Program 1: A sample C++ Program
The first
two lines in the programs are
// Filename : program01.cpp
// Purpose : A Simple C++ Program
These lines
begin with // (double forward slash), these are line comments.
C++ support two type of comments: -
Block
comments – Traditional C style comments
/*anything within this pair of forward slash, asterisk and asterisk, forward
slash is a comment, this may be a part of the line or may be multiline*/
Line
comments – C++ style comments
// anything on this line after a pair of forward slash up to end of line is a
comment.
// If we need more than one line, every line must begin with double forward
slash
The third
line is
#include <iostream>
It begins
with # (hash or pond), it is preprocessor directive. Any line that begins with
a # is a preprocessor directive that instructs the preprocessor to follow the
instruction given by the following command (include in this case).
This is same as in C and copies the content of the file "iostream" at this place.
The file
included here is iostream. Note that this does not
have ".h" extension. In fact, it is standard C++ style header file.
(Traditional style headers were having .h extension like iostream.h). This header supports C++ style I/O
operations.
Caution!!! Turbo C++ 3.0 IDE does not support Standard C++, it
supports only Traditional C++. To use all features on Standard C++, you may use
any new compiler and IDE. Turbo C++ 4.5, Borland C++ 5.0, Microsoft Visual C++,
or Developer C++ 5 may work fine. A support for Standard C++ is inbuilt in most
of Linux distributions. On windows, I recommend to install Developer C++ 5
(4.9.9.1) which may be obtained freely from Internet or over windows share
//campus/public/software (preferred in campus).
The next
line in the program is
using namespace std;
This tells
the compiler to use the std (standard)
namespace. Namespaces are a recent addition to C++. A namespace creates a
declarative region in which various program elements can be placed. Namespaces
help in the organization of large programs.
The using
statement informs the compiler that you want to use the std
namespace. This is the namespace in which the entire C++ library is
declared. By using the std namespace,
you simply use the standard library.
Now examine
the following line
int main()
This line
simply tells that the function main takes no parameter and returns an
integer value. In C++, an empty argument list like main ( ) simply declares that
the function take no parameter, the use of void like main (void) is
redundant and unnecessary.
As far as
the return value is concerned, you may not use void main ( ), as
standard C++ does not permit the return type of main to be void. The main
function must return an integer value.
Note:
This is in contrast to tradition C/C++, where you may have used void as the
preferred type of return value for main.
The {, opening brace and }, closing brace enclose the body of
the main as in C.
The next line
is an output statement
cout << "Hello! What is your age: ";
This line
causes the string "Hello! What is your age: " to
be printed over output device (monitor). In C++, cout
(pronounced as see out) is an object of ostream class
and << is the insertion operator (in addition to the existing role of
left shift operator since C). The insertion operator inserts the data on its
right in the output stream through an object of ostream
class (cout in this case), which flows from CPU to
output device (monitor by default).
The next
line is
int age;
This is
variable declaration like C. But, not is the beginning, Hum! C++ allows the
declaration of variables anywhere in the program in contrast to C, which allows
the declaration of variables only in declaration section before any executable
statement.
The next line is
cin >> age;
This line
reads an integer value from key board and stores it in the variable age. In
C++, cin (pronounced as see in) is an object
of istream class and >> is the
extraction operator (in addition to the existing role of right shift operator
since C). The extraction operator extracts the data from input stream through
an object of istream class (cin
in this case), which flows from input device (key board by default) to the CPU
and stores it in the variable or object on its right.
The next
line is
cout<< "Welcome, you
are "<<age<<" years old."<<endl;
This is
same as the previous output statement but here, multiple << (insertion
operators) are used to insert multiple data items of different types into a
single object (cout). This is called cascading. Both
insertion & extraction operators may be cascaded in this way.
The last
word endl is an output manipulator which
is used to cause linefeed in C++.
The next
line is
system ("pause");
This is
same as in C, calls system function (operating system) with "pause"
as parameter, which is a DOS command ported in Windows 9x/NT series and causes
the display to halt (pause) until a key is pressed. It also prompts a message
"Press a key to continue…"
Caution!!! Do not use clrscr( ) & getch( ), these are exclusive Borland implementations and
are not standard, hence not portable. Instead, use system ("cls") and system ("pause") on windows and
system ("clear") and system ("pause") on Linux.
The last
line is
return 0;
This return
backs the control to the operating system and passes an integer 0, indicating
that there was ZERO ERROR during execution.
The output
on execution of this program is
Hello!
What is your age:
You are
expected to input an integer value here e.g. 17
Now the
program reads the value typed and proceeds further to display
Welcome,
you are 17 years old.
Press
any key to continue . . .