CPP Classes and Objects

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-plus-cpp-tutorial/">C++ lies the concept of classes, which forms the cornerstone of object-oriented programming, often denoted as user-defined types. Object-Oriented Programming (OOP) in C++ allows for the creation of structured and modular code by organizing data and functions into classes and objects.

Defining Classes in C++ Programming Language

A class serves as the blueprint for constructing a data type. While it doesn’t directly manifest data, it intricately defines the essence of the class name – specifying the composition of objects belonging to the class and the range of actions that can be executed on these objects.

The structure of a class definition commences with the keyword class, followed by the designated class name, encapsulated within a set of curly braces. The class definition is concluded by either a semicolon or an enumeration of declarations. To illustrate, we establish the Box data type utilizing the class keyword:

class Box {
   public:
      double length;   // Dimension - length
      double breadth;  // Dimension - breadth
      double height;   // Dimension - height
};

In this instance, the keyword public determines the accessibility attributes of the ensuing class members. Public members can be accessed from external to the class, anywhere within the confines of the class object. Additionally, the option exists to designate class members as private or protected, a topic to be addressed in a subsequent section.

Constructing C++ Objects

A class furnishes the framework for generating objects; effectively, an object is synthesized from a class. The declaration of objects of a class follows a format akin to that of declaring variables with fundamental data types. The ensuing statements exemplify the declaration of two Box class objects:

Box Box1;          // Declaration of Box1, of type Box
Box Box2;          // Declaration of Box2, of type Box

Both Box1 and Box2 attain individual replicas of the data members they incorporate.

Accessing Data Members

Public data members associated with class objects are accessible through the utilization of the direct member access operator .. The ensuing example elucidates this process:

#include <iostream>

using namespace std;

class Box {
   public:
      double length;   // Dimension - length
      double breadth;  // Dimension - breadth
      double height;   // Dimension - height
};

int main() {
   Box Box1;        // Declaration of Box1, of type Box
   Box Box2;        // Declaration of Box2, of type Box
   double volume = 0.0;     // Storage for box volume

   // Specification for Box1
   Box1.height = 5.0; 
   Box1.length = 6.0; 
   Box1.breadth = 7.0;

   // Specification for Box2
   Box2.height = 10.0;
   Box2.length = 12.0;
   Box2.breadth = 13.0;

   // Volume computation for Box1
   volume = Box1.height * Box1.length * Box1.breadth;
   cout << "Volume of Box1 : " << volume << endl;

   // Volume computation for Box2
   volume = Box2.height * Box2.length * Box2.breadth;
   cout << "Volume of Box2 : " << volume << endl;
   return 0;
}

This example succinctly demonstrates the computation of volumes for Box1 and Box2 objects.

Delving Deeper: Classes and Objects in C++

Though the foundational concepts of C++ classes and objects have been introduced, a plethora of captivating concepts remains to be explored. These concepts, each endowed with its distinctive significance, are enumerated below:

1. Class Member Functions: A class’s member function is a function intrinsically characterized by its definition or prototype housed within the class definition, resembling the treatment of any other variable.
2. Class Access Modifiers: Members of a class can be classified as public, private, or protected. By default, class members are assumed to be private.
3. Constructor & Destructor: A class constructor is an exceptional function that is invoked upon the creation of a new object of the class. Conversely, a destructor is a special function engaged when an existing object is deleted.
4. Copy Constructor: The copy constructor fabricates an object by initializing it with an object of the same class, which was instantiated previously.
5. Friend Functions: Friend functions are granted comprehensive access to the private and protected components of a class.
6. Inline Functions: An inline function triggers the compiler to expand the code in the function’s body in lieu of invoking the function.
7. The “this” Pointer: Each object is accompanied by a unique pointer, denoted as this, which points directly to the object itself.
8. Pointer to C++ Classes: Pointers to classes are treated analogously to pointers to structures. Indeed, a class essentially mirrors a structure, complemented by encapsulated functions.
9. Static Members of a Class: Both data members and function members within a class can be assigned the static attribute.

In conclusion, the world of C++ programming is a rich tapestry woven with classes and objects, embodying multifarious dimensions and possibilities. This comprehensive guide is the first step toward unlocking the boundless potential of C++.