CODEWITHSUNDEEP
pythonrecursion
Kenneth
Kenneth

Reputation: 45

Why my function won't stop even if the condition is True?

I'm testing if the word number is the power of 2 by log function. If the word number is low, I append the word by '.' until the length becomes the power of 2. Eg, If the word(W) is 'abcd', the len(W) = 4, which is 2^2. The function will stop. If the W is 'abcdef', the len(W) = 6, I want to append the word by '.', so it becomes 'abcdef..' The new W length is 8, which is 2^3.

Please check where I need to make changes. 

import math

def powerOf2(W):
    logP = math.log2(len(W))
    if isinstance(logP, int):
        return W
    else:
        W.append('.')
        powerOf2(W)

When I run 

W = list('abcd')
powerOf2(W)

The program stops with "maximum recursion". I thought the condition is true. What seems to be a problem?

Working script. I changed the isinstance function.

import math

def powerOf2(W):
    logP = math.log2(len(W))
    if (logP).is_integer():
        return W
    else:
        W.append('.')
        powerOf2(W)

Upvotes: 0

Views: 47

Answers (1)

TMarafon
TMarafon

Reputation: 337

You need to return the recursion:

import math

def powerOf2(W):
    logP = math.log2(len(W))
    if isinstance(logP, int):
        return W
    else:
        W.append('.')
        return powerOf2(W)

Upvotes: 2

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