如何计算 python 中带前导零的数字的位数

Question

In a number without leading zeroes I would do this

import math
num = 1001
digits = int(math.log10(num))+1
print (digits)

>>> 4

but if use a number with leading zeroes like "0001" I get

SyntaxError: leading zeros in decimal integer literals are not permitted; use an 0o prefix for octal integers

I would like to be able to count the digits including the leading zeroes. What would be the best way to achieve this?

Answer 1

You can't reasonably have a number with leading digits unless it's a string!

Therefore, if you're accepting a string, just remove them and check the difference in length

>>> value         = input("enter a number: ")
enter a number: 0001
>>> value_clean   = value.lstrip("0")
>>> leading_zeros = len(value) - len(value_clean)
>>> print("leading zeros: {}".format(leading_zeros))
leading zeros: 3

If you only wanted the number from a bad input, int() can directly convert it for you instead

>>> int("0001")
1

Answer 2

I'm dumb.The answer was simple. All I needed was:

num = 0001
num_string = str(num) 
print (len(num_string))

result:

>>> 4