All objects share class or static variables. An instance or non-static variables are different for different objects (every object has a copy). For example, let a Computer Science Student be represented by class CSStudent. The class may have a static variable whose value is “cse” for all objects. And class may also have non-static members like name and roll. In C++ and Java, we can use static keywords to make a variable a class variable. The variables which don’t have a preceding static keyword are instance variables. See this for Java example and this for C++ example.
The Python approach is simple; it doesn’t require a static keyword.
All variables which are assigned a value in the class declaration are class variables. And variables that are assigned values inside methods are instance variables.
Python
# Python program to show that the variables with a value # assigned in class declaration, are class variables# Class for Computer Science Studentclass CSStudent: stream = 'cse' # Class Variable def __init__(self,name,roll): self.name = name # Instance Variable self.roll = roll # Instance Variable# Objects of CSStudent classa = CSStudent('Geek', 1)b = CSStudent('Nerd', 2)print(a.stream) # prints "cse"print(b.stream) # prints "cse"print(a.name) # prints "Geek"print(b.name) # prints "Nerd"print(a.roll) # prints "1"print(b.roll) # prints "2"# Class variables can be accessed using class# name alsoprint(CSStudent.stream) # prints "cse"# Now if we change the stream for just a it won't be changed for ba.stream = 'ece'print(a.stream) # prints 'ece'print(b.stream) # prints 'cse'# To change the stream for all instances of the class we can change it # directly from the classCSStudent.stream = 'mech'print(a.stream) # prints 'mech'print(b.stream) # prints 'mech' |
Output:
cse cse Geek Nerd 1 2 cse ece cse ece mech
This article is contributed by Harshit Gupta. If you like GeeksforGeeks and would like to contribute, you can also write an article and mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above
Attention geek! Strengthen your foundations with the Python Programming Foundation Course and learn the basics.
To begin with, your interview preparations Enhance your Data Structures concepts with the Python DS Course.
