Search⌘ K
Home
Courses
Learn C++ Fundamentals

Introduction to Classes

Learn about classes using object-oriented methodology.

We'll cover the following...

Building blocks of object-oriented programming

Class is the building block of a program built using the object-oriented methodology. Such programs consist of independent, self-managing modules and their interactions. An object is an instance of such a module created at runtime, and a class is its definition.

Class definition and instantiation

A class definition includes the declaration of its data members (data variables) and member functions (class functions), whereas instantiation is the process of creating an actual object. This object can then be used to access the data members and member functions defined in the class.

C++
class className 
{
  variable var1           // Variables names can be of type string, int, float
  variable var2          
  variable* ptr;          // Pointer variable for var1 or var2, can be of any type
};               // Class body always terminates with ';'

A keyword class is used with every declaration of class, followed by the name of the class. We can use any “className” you want, as long as it follows the naming rules that we defined previously in the context of variables.

We can also initialize our class data members at the time of declaration, like we can do with simple variables. Here’s how we can initialize our data members with default values for the class demoClass.

C++
class demoClass 
{
  int var1 = 25;        
  string name = "nimra"          
};

Let’s look at an example of creating a Dog class and using it to learn about classes in detail.

C++
class Dog{
  public:
      string name;
      string gender;
      int age;
      int size;
      bool healthy;
};
int main(){
  Dog dogObj;     // Creating an object of Dog class called DogObj
}
...