TypeError: must be real number, not Circle

import math as m
class Circle:
def __init__(self,radius):
self.radius = radius
count = 0
def area(r):
k = m.pi * m.pow(r,2)
return k


I am not sure what wrong with the code above but when I am trying execute like below

a = Circle(4)
a.area()
it throws an error like
" k = m.pi * m.pow(r,2)
TypeError: must be real number, not Circle"


Unable to understand how it's considering the float value as an instance to the circle.

import math as m

2 Answers
2

The first argument of an instance method is a reference to the instance itself (usually called self) - that's where the Circe is coming from. You shouldn't be passing the radius, you should be using the member you have:

self

def area(self):
k = m.pi * m.pow(self.radius, 2)
return k


import math as m
DEFAULT_RADIUS = 0.5
class Circle(object):
def __init__(self, radius=DEFAULT_RADIUS):
self.radius = radius
count = 0
def area(self, r=None):
if r is not None:
self.radius = r
k = m.pi * m.pow(self.radius, 2)
return k
a = Circle(4)
a.area()


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