Classes and Objects
A class is a definition of an object. It's a type just like int. A class resembles a struct with just one difference : all struct members are public by default. All classes members are private.Remember : A class is a type, and an object of this class is just a variable.
Before we can use an object, it must be created. The simplest definition of a class is
class name {This example class below models a simple book. Using OOP lets you abstract the problem and think about it and not just arbitrary variables.
// members
}
// example oneAll the code from class book down to the int Book::GetCurrentPage(void) { function is part of the class. The main() function is there to make this a runnable application.
#include <iostream>
#include <stdio.h>
class Book
{
int PageCount;
int CurrentPage;
public:
Book( int Numpages) ; // Constructor
~Book(){} ; // Destructor
void SetPage( int PageNumber) ;
int GetCurrentPage( void ) ;
};
Book::Book( int NumPages) {
PageCount = NumPages;
}
void Book::SetPage( int PageNumber) {
CurrentPage=PageNumber;
}
int Book::GetCurrentPage( void ) {
return CurrentPage;
}
int main() {
Book ABook(128) ;
ABook.SetPage( 56 ) ;
std::cout << "Current Page " << ABook.GetCurrentPage() << std::endl;
return 0;
}
On the next page : Understanding the example.
