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python - python编程错误RecursionError：比较超过最大递归深度

问题描述

这是我的python程序，也是我提出的练习6.4答案。

#!/usr/bin/env python3

"""
Exercise 6.4.
A number, a, is a power of b if it is divisible by b and a/b is a power of b.
Write a function called is_power that takes parameters a and b and returns
True if a is a power of b.
Note: you will have to think about the base case.
"""

def is_power(a, b):
    """Checks if a is power of b."""
    if a == b:
        return True
    elif a%b == 0:
        return is_power(a/b, b)
    else:
        return False

print("is_power(10, 2) returns: ", is_power(10, 2))
print("is_power(27, 3) returns: ", is_power(27, 3))
print("is_power(1, 1)  returns: ",  is_power(1, 1))
print("is_power(10, 1) returns: ", is_power(10, 1))
print("is_power(3, 3)  returns: ",  is_power(3, 3))

每当我一次又一次地尝试显示此错误时，我都会收到此错误。请指导我程序中的错误在哪里。

is_power(10, 2) returns:  False
is_power(27, 3) returns:  True
is_power(1, 1)  returns:  True
Traceback (most recent call last):
  File "C:\Users\Aaban Shakeel\Desktop\Think-Python-2e---my-solutions-master\ex6\ex6.4.py", line 23, in <module>
    print("is_power(10, 1) returns: ", is_power(10, 1))
  File "C:\Users\Aaban Shakeel\Desktop\Think-Python-2e---my-solutions-master\ex6\ex6.4.py", line 16, in is_power
    return is_power(a/b, b)
  File "C:\Users\Aaban Shakeel\Desktop\Think-Python-2e---my-solutions-master\ex6\ex6.4.py", line 16, in is_power
    return is_power(a/b, b)
  File "C:\Users\Aaban Shakeel\Desktop\Think-Python-2e---my-solutions-master\ex6\ex6.4.py", line 16, in is_power
    return is_power(a/b, b)
  [Previous line repeated 1021 more times]
  File "C:\Users\Aaban Shakeel\Desktop\Think-Python-2e---my-solutions-master\ex6\ex6.4.py", line 13, in is_power
    if a == b:
RecursionError: maximum recursion depth exceeded in comparison

标签： pythonpython-3.x

解决方案

这是因为对于b=1，您的递归将永远不会结束 - 我会添加：

def is_power(a, b):
    """Checks if a is power of b."""
    if a == b:
        return True
    elif b==1:
        return False
    elif a%b == 0:
        return is_power(a/b, b)
    else:
        return False

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