Explain the output of this python script?

Question

For counting number of zero's in a number ..

def cal(l):
    r = 0
    o = 0
    while (r == 0):
        r = l % 10
        o += 1
        l = int(l / 10)
    return o-1

So when the input is greater than 10^23 output is 1. Why does this happen?

SuperStormer · Accepted Answer · 2021-03-10 18:58:28Z

4

int(l / 10) is floating point division, which is inaccurate as your numbers grow larger(more info). Change it to l // 10, which is integer division and has no accuracy issues.

answered Mar 10, 2021 at 18:58

SuperStormer

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Comments

Timur Shtatland · Accepted Answer · 2021-03-10 19:20:50Z

2

Do not use arithmetic operations to count characters. Use string operations instead, for example str.count for simple strings, or re.findall for something more complex, which requires regular expressions:

import re
for n in [1, 0.1, 10.0, 10**23, 10**24]:
    print(str(n).count('0'))
    # or this:
    # print(len(re.findall(r'0', str(n))))
# 0
# 1
# 2
# 23
# 24

edited Mar 10, 2021 at 19:20

answered Mar 10, 2021 at 19:14

Timur Shtatland

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2 Comments

SuperStormer Over a year ago

str.count instead of re?

Timur Shtatland Over a year ago

@SuperStormer: Thank you for the suggestion to use a simpler str.count instead of re. Updated the answer.

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