What is Constructor?

A constructor is a special type of method used in object-oriented programming languages to initialize objects. The constructor is called automatically every time when an object is created, allowing the object to set initial values for its attributes or perform other setup tasks.

In this article, we will learn about constructor, its variant and their use cases in C++, Python and Java.

What is a Constructor?

In programming, particularly in languages like Java, C++, Python, and others, a constructor is used to allocate memory and initialize the state of a new object. Constructors have the same name as the class and do not have a return type, not even `void`.

Syntax of Constructor in Python

Below is the syntax of constructor in Python:

class ClassName:
    def __init__(self):
        # initialization code
        pass

Syntax of Constructor in Java

Below is the syntax of constructor in Java:

class ClassName {
    // Constructor
    ClassName() {
        // initialization code
    }
}

Syntax of Constructor in C++

Below is the syntax of constructor in C++:

class ClassName {
public:
    // Constructor
    ClassName() {
        // initialization code
    }
};

Types of Constructors

Types of constructors are nothing but the overloaded versions of the constructor that allows the creation and initialization of objects in different ways. The types of constructors are language specific:

Types of Constructors in Python

• Default Constructor
• Parameterized Constructor

Types of Constructors in Java

• Default Constructor
• Parameterized Constructor
• Copy Constructor

Types of Constructors in C++

• Default Constructor
• Parameterized Constructor
• Copy Constructor
• Move Constructor

Applications of Constructors

Following are the major applications of constructors:

• Constructors are mainly used to initialize the attributes of an object when it is created.
• Constructors can set default values for attributes. This ensures that the newly created objects are in a valid state.
• Different constructor types allow us to create objects in different ways.
• Constructor allows user to manage the object resource allocation.

Conclusion

Constructor is one of the basic and important aspects of object-oriented programming which are used to define how objects should be created and initialized. They make a guarantee that the newly created object is in a valid state.