Constructors in Python
Prerequisites : Object Oriented Programming in Python, Object Oriented Programming in Python | Set 2
Constructors are generally used for instantiating an object.The task of constructors is to initialize(assign values) to the data members of the class when an object of class is created.In Python the __init__() method is called the constructor and is always called when an object is created.
Syntax of constructor declaration :
def __init__(self):
# body of the constructor
Types of constructors :
- default constructor :The default constructor is simple constructor which doesn’t accept any arguments.It’s definition has only one argument which is a reference to the instance being constructed.
- parameterized constructor :constructor with parameters is known as parameterized constructor.The parameterized constructor take its first argument as a reference to the instance being constructed known as self and the rest of the arguments are provided by the programmer.
Example of default constructor :
class GeekforGeeks: geek = "" # default constructor def __init__(self): self.geek = "GeekforGeeks" # a method for printing data members def print_Geek(self): print(self.geek) # creating object of the class obj = GeekforGeeks() # calling the instance method using the object obj obj.print_Geek() |
chevron_right
filter_none
Output :
GeekforGeeks
Example of parameterized constructor :
class Addition: first = 0 second = 0 answer = 0 # parameterized constructor def __init__(self, f, s): self.first = f self.second = s def display(self): print("First number = " + str(self.first)) print("Second number = " + str(self.second)) print("Addition of two numbers = " + str(self.answer)) def calculate(self): self.answer = self.first + self.second # creating object of the class # this will invoke parameterized constructor obj = Addition(1000, 2000) # perform Addition obj.calculate() # display result obj.display() |
chevron_right
filter_none
Output :
First number = 1000 Second number = 2000 Addition of two numbers = 3000
Recommended Posts:
- Perl | Constructors and Destructors
- Difference between the Constructors and Methods
- Important differences between Python 2.x and Python 3.x with examples
- Python | Sort Python Dictionaries by Key or Value
- Python | Set 4 (Dictionary, Keywords in Python)
- bin() in Python
- try and except in Python
- chr() in Python
- Python Set | pop()
- set add() in python
- Python | a += b is not always a = a + b
- zip() in Python
- gcd() in Python
- SHA in Python
- pow() in Python
If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.
