C++ Programming Code Examples
C++ > Beginners Lab Assignments Code Examples
Class for Library
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/* Class for Library */
# include<iostream.h>
# include<conio.h>
// Creating a basic template for book and magazine
class lib
{
private:
char title[20];
char pub[20];
unsigned int acc_no;
public:
//method for getting inputs
void get_details()
{
cout<<"Enter the book title"<<endl;
cin>>title;
cout<<"Enter the publisher name"<<endl;
cin>>pub;
cout<<"Enter the accession number"<<endl;
cin>>acc_no;
}
//method for showing output
void show_details()
{
cout<<"Title : "<<title<<endl;
cout<<"Publisher : "<<pub<<endl;
cout<<"Accession No. : "<<acc_no<<endl;
}
};
// Class Book derived from lib
class book : private lib
{
private:
char author[20];
public:
void get_details()
{
lib::get_details();
cout<<"Enter the author's name: "<<endl;
cin>>author;
}
void show_details()
{
lib::show_details();
cout<<"Autohr : "<<author<<endl;
}
};
//Class for Magazine derived from lib
class magz : private lib
{
private:
char editor[20];
public:
void get_details()
{
lib::get_details();
cout<<"Enter the editor's name: "<<endl;
cin>>editor;
}
void show_details()
{
lib::show_details();
cout<<"editor : "<<editor<<endl;
}
};
void main(void)
{
clrscr();
//creating objects
book b;
magz m;
b.get_details();
m.get_details();
b.show_details();
m.show_details();
getch();
}
A program shall contain a global function named main, which is the designated start of the program in hosted environment. main() function is the entry point of any C++ program. It is the point at which execution of program is started. When a C++ program is executed, the execution control goes directly to the main() function. Every C++ program have a main() function.
It is a predefined function in "conio.h" (console input output header file) used to clear the console screen. It is a predefined function, by using this function we can clear the data from console (Monitor). Using of clrscr() is always optional but it should be place after variable or function declaration only. It is often used at the beginning of the program (mostly after variable declaration but not necessarily) so that the console is clear for our output.
The main purpose of C++ programming is to add object orientation to the C programming language and classes are the central feature of C++ that supports object-oriented programming and are often called user-defined types. A class is used to specify the form of an object and it combines data representation and methods for manipulating that data into one neat package. The data and functions within a class are called members of the class.
The cin object is used to accept input from the standard input device i.e. keyboard. It is defined in the iostream header file. C++ cin statement is the instance of the class istream and is used to read input from the standard input device which is usually a keyboard. The extraction operator(>>) is used along with the object cin for reading inputs. The extraction operator extracts the data from the object cin which is entered using the keyboard. The "c" in cin refers to "character" and "in" means "input". Hence cin means "character input". The cin object is used along with the extraction operator >> in order to receive a stream of characters.
A predefined object of the class called iostream class is used to insert the new line characters while flushing the stream is called endl in C++. This endl is similar to \n which performs the functionality of inserting new line characters but it does not flush the stream whereas endl does the job of inserting the new line characters while flushing the stream. Hence the statement cout<<endl; will be equal to the statement cout<< '\n' << flush; meaning the new line character used along with flush explicitly becomes equivalent to the endl statement in C++.
The getch() is a predefined non-standard function that is defined in conio.h header file. It is mostly used by the Dev C/C++, MS- DOS's compilers like Turbo C to hold the screen until the user passes a single value to exit from the console screen. It can also be used to read a single byte character or string from the keyboard and then print. It does not hold any parameters. It has no buffer area to store the input character in a program. The getch() function does not accept any parameter from the user. It returns the ASCII value of the key pressed by the user as an input.
#include is a way of including a standard or user-defined file in the program and is mostly written at the beginning of any C/C++ program. This directive is read by the preprocessor and orders it to insert the content of a user-defined or system header file into the following program. These files are mainly imported from an outside source into the current program. The process of importing such files that might be system-defined or user-defined is known as File Inclusion. This type of preprocessor directive tells the compiler to include a file in the source code program.
The cout is a predefined object of ostream class. It is connected with the standard output device, which is usually a display screen. The cout is used in conjunction with stream insertion operator (<<) to display the output on a console. On most program environments, the standard output by default is the screen, and the C++ stream object defined to access it is cout. The "c" in cout refers to "character" and "out" means "output". Hence cout means "character output". The cout object is used along with the insertion operator << in order to display a stream of characters.
In C++, constructor is a special method which is invoked automatically at the time of object creation. It is used to initialize the data members of new object generally. The constructor in C++ has the same name as class or structure. Constructors are special class functions which performs initialization of every object. The Compiler calls the Constructor whenever an object is created. Constructors initialize values to object members after storage is allocated to the object. Whereas, Destructor on the other hand is used to destroy the class object. • Default Constructor: A constructor which has no argument is known as default constructor. It is invoked at the time of creating object.
The object should calculate the 'total area' & the volume based on the side measurement. If the program supplies a side equal or lower than 0, reset the side to 1. "Create an empty"
