Code Explanation:
1. Defining the Class
class Counter:
A class named Counter is defined.
2. Defining a Class Variable
total = 0
total is a class variable.
It belongs to the class Counter, not to any specific object.
Initially:
Counter.total == 0
3. Defining the Method inc
def inc(self):
self.total += 1
This line is the key trap.
self.total += 1 is equivalent to:
self.total = self.total + 1
Python first reads self.total:
No total in the instance → falls back to Counter.total (0)
Python then assigns to self.total:
This creates a new instance variable named total.
4. Creating Two Objects
a = Counter()
b = Counter()
Two separate instances are created.
At this point:
a.__dict__ == {}
b.__dict__ == {}
Counter.total == 0
5. Calling inc() on a
a.inc()
Step-by-step:
self.total → reads Counter.total → 0
Adds 1 → result 1
Assigns back to instance:
a.total = 1
After this:
a.__dict__ == {'total': 1}
b.__dict__ == {}
Counter.total == 0
6. Printing the Values
print(a.total, b.total, Counter.total)
a.total → instance variable → 1
b.total → no instance variable → uses class variable → 0
Counter.total → class variable → 0
7. Final Output
1 0 0
✅ Final Answer
✔ Output:
1 0 0
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