getting zeros from an integer using python recursion

January 9, 2022

I want to extract all the zeros from a number and find the length of the number of zeros using Python recursion. I’ve tried the following code but it gives me an error. I can do that using for loop but I want to know how python recursion does this. For this code output should be 3.

def zeros(n):
    x = list(str(n))
    if x == []:
        return []
    else:
        head = x[0]
        tail = "0"
        return len([head]) + zeros(tail)


print(zeros(10010))

RecursionError: maximum recursion depth exceeded while calling a Python object

>Solution :

because after first loop , head is always a scalar value (number) and tail is always 0 , so always the else part of your logic runs and there is no logic to stop the recursion for a specific condition, and eventually it hits the recursion limit with the error message you got.

you can count number of occurrence of zeros in a number this way easily: