number_of_digits.py

importmath
fromtimeitimporttimeit


defnum_digits(n: int) ->int:
"""
 Find the number of digits in a number.

 >>> num_digits(12345)
 5
 >>> num_digits(123)
 3
 >>> num_digits(0)
 1
 >>> num_digits(-1)
 1
 >>> num_digits(-123456)
 6
 >>> num_digits('123') # Raises a TypeError for non-integer input
 Traceback (most recent call last):
 ...
 TypeError: Input must be an integer
 """

ifnotisinstance(n, int):
raiseTypeError("Input must be an integer")

digits=0
n=abs(n)
whileTrue:
n=n//10
digits+=1
ifn==0:
break
returndigits


defnum_digits_fast(n: int) ->int:
"""
 Find the number of digits in a number.
 abs() is used as logarithm for negative numbers is not defined.

 >>> num_digits_fast(12345)
 5
 >>> num_digits_fast(123)
 3
 >>> num_digits_fast(0)
 1
 >>> num_digits_fast(-1)
 1
 >>> num_digits_fast(-123456)
 6
 >>> num_digits('123') # Raises a TypeError for non-integer input
 Traceback (most recent call last):
 ...
 TypeError: Input must be an integer
 """

ifnotisinstance(n, int):
raiseTypeError("Input must be an integer")

return1ifn==0elsemath.floor(math.log(abs(n), 10) +1)


defnum_digits_faster(n: int) ->int:
"""
 Find the number of digits in a number.
 abs() is used for negative numbers

 >>> num_digits_faster(12345)
 5
 >>> num_digits_faster(123)
 3
 >>> num_digits_faster(0)
 1
 >>> num_digits_faster(-1)
 1
 >>> num_digits_faster(-123456)
 6
 >>> num_digits('123') # Raises a TypeError for non-integer input
 Traceback (most recent call last):
 ...
 TypeError: Input must be an integer
 """

ifnotisinstance(n, int):
raiseTypeError("Input must be an integer")

returnlen(str(abs(n)))


defbenchmark() ->None:
"""
 Benchmark multiple functions, with three different length int values.
 """
fromcollections.abcimportCallable

defbenchmark_a_function(func: Callable, value: int) ->None:
call=f"{func.__name__}({value})"
timing=timeit(f"__main__.{call}", setup="import __main__")
print(f"{call}: {func(value)} -- {timing} seconds")

forvaluein (262144, 1125899906842624, 1267650600228229401496703205376):
forfuncin (num_digits, num_digits_fast, num_digits_faster):
benchmark_a_function(func, value)
print()


if__name__=="__main__":
importdoctest

doctest.testmod()
benchmark()