- 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.
- 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 - Sample - python code :
# 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('wiki', 1)
b = CSStudent('techy', 2)
print(a.stream) # prints "cse"
print(b.stream) # prints "cse"
print(a.name) # prints "wiki"
print(b.name) # prints "techy"
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 wiki techy 1 2 cse