Class or static variables are shared by all objects. Instance or non-static variables are different for different objects (every object has a copy of it).
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 keyword to make a variable as class variable. The variables which don’t have 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 class declaration are class variables. And variables which are assigned values inside class methods are instance variables.
# Python program to show that the variables with a value # assigned in class declaration, are class variables # Class for Computer Science Student class CSStudent: stream = 'cse' # Class Variable def __init__(self,name,roll): self.name = name # Instance Variable self.roll = roll # Instance Variable # Objects of CSStudent class a = 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 also print(CSStudent.stream) # prints "cse" |
Output:
cse cse Geek Nerd 1 2 cse
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