在Python中，如何找到整数中的位数?
当前回答
正如亲爱的用户@Calvintwr提到的，函数数学。Log10在一个超出范围[-999999999999997,99999999999999997]的数字中有问题，我们会得到浮点数错误。我有这个问题与JavaScript(谷歌V8和NodeJS)和C (GNU GCC编译器)，所以一个“纯数学”的解决方案是不可能在这里。
基于这个要点和答案，亲爱的用户@Calvintwr
import math
def get_count_digits(number: int):
"""Return number of digits in a number."""
if number == 0:
return 1
number = abs(number)
if number <= 999999999999997:
return math.floor(math.log10(number)) + 1
count = 0
while number:
count += 1
number //= 10
return count
我在长度不超过20(包括20)的数字上进行了测试，没问题。它必须足够，因为64位系统上的最大整数长度是19 (len(str(sys.maxsize)) == 19)。
assert get_count_digits(-99999999999999999999) == 20
assert get_count_digits(-10000000000000000000) == 20
assert get_count_digits(-9999999999999999999) == 19
assert get_count_digits(-1000000000000000000) == 19
assert get_count_digits(-999999999999999999) == 18
assert get_count_digits(-100000000000000000) == 18
assert get_count_digits(-99999999999999999) == 17
assert get_count_digits(-10000000000000000) == 17
assert get_count_digits(-9999999999999999) == 16
assert get_count_digits(-1000000000000000) == 16
assert get_count_digits(-999999999999999) == 15
assert get_count_digits(-100000000000000) == 15
assert get_count_digits(-99999999999999) == 14
assert get_count_digits(-10000000000000) == 14
assert get_count_digits(-9999999999999) == 13
assert get_count_digits(-1000000000000) == 13
assert get_count_digits(-999999999999) == 12
assert get_count_digits(-100000000000) == 12
assert get_count_digits(-99999999999) == 11
assert get_count_digits(-10000000000) == 11
assert get_count_digits(-9999999999) == 10
assert get_count_digits(-1000000000) == 10
assert get_count_digits(-999999999) == 9
assert get_count_digits(-100000000) == 9
assert get_count_digits(-99999999) == 8
assert get_count_digits(-10000000) == 8
assert get_count_digits(-9999999) == 7
assert get_count_digits(-1000000) == 7
assert get_count_digits(-999999) == 6
assert get_count_digits(-100000) == 6
assert get_count_digits(-99999) == 5
assert get_count_digits(-10000) == 5
assert get_count_digits(-9999) == 4
assert get_count_digits(-1000) == 4
assert get_count_digits(-999) == 3
assert get_count_digits(-100) == 3
assert get_count_digits(-99) == 2
assert get_count_digits(-10) == 2
assert get_count_digits(-9) == 1
assert get_count_digits(-1) == 1
assert get_count_digits(0) == 1
assert get_count_digits(1) == 1
assert get_count_digits(9) == 1
assert get_count_digits(10) == 2
assert get_count_digits(99) == 2
assert get_count_digits(100) == 3
assert get_count_digits(999) == 3
assert get_count_digits(1000) == 4
assert get_count_digits(9999) == 4
assert get_count_digits(10000) == 5
assert get_count_digits(99999) == 5
assert get_count_digits(100000) == 6
assert get_count_digits(999999) == 6
assert get_count_digits(1000000) == 7
assert get_count_digits(9999999) == 7
assert get_count_digits(10000000) == 8
assert get_count_digits(99999999) == 8
assert get_count_digits(100000000) == 9
assert get_count_digits(999999999) == 9
assert get_count_digits(1000000000) == 10
assert get_count_digits(9999999999) == 10
assert get_count_digits(10000000000) == 11
assert get_count_digits(99999999999) == 11
assert get_count_digits(100000000000) == 12
assert get_count_digits(999999999999) == 12
assert get_count_digits(1000000000000) == 13
assert get_count_digits(9999999999999) == 13
assert get_count_digits(10000000000000) == 14
assert get_count_digits(99999999999999) == 14
assert get_count_digits(100000000000000) == 15
assert get_count_digits(999999999999999) == 15
assert get_count_digits(1000000000000000) == 16
assert get_count_digits(9999999999999999) == 16
assert get_count_digits(10000000000000000) == 17
assert get_count_digits(99999999999999999) == 17
assert get_count_digits(100000000000000000) == 18
assert get_count_digits(999999999999999999) == 18
assert get_count_digits(1000000000000000000) == 19
assert get_count_digits(9999999999999999999) == 19
assert get_count_digits(10000000000000000000) == 20
assert get_count_digits(99999999999999999999) == 20
所有使用Python 3.5测试的代码示例
其他回答
如果你想要一个整数的长度等于这个整数的位数，你总是可以把它转换成字符串，比如str(133)，然后像len(str(123))一样找到它的长度。
假设您要求的是可以存储在整数中的最大数字，则该值与实现有关。我建议你在使用python时不要这样想。在任何情况下，相当大的值都可以存储在python 'integer'中。记住，Python使用鸭子类型!
编辑: 我在澄清提问者想要数字数之前给出了我的答案。就此而言，我同意公认答案所建议的方法。没什么可补充的了!
如果您正在寻找一个不使用内置函数的解决方案。 唯一需要注意的是当你发送a = 000时。
def number_length(a: int) -> int:
length = 0
if a == 0:
return length + 1
else:
while a > 0:
a = a // 10
length += 1
return length
if __name__ == '__main__':
print(number_length(123)
assert number_length(10) == 2
assert number_length(0) == 1
assert number_length(256) == 3
assert number_length(4444) == 4
正如亲爱的用户@Calvintwr提到的，函数数学。Log10在一个超出范围[-999999999999997,99999999999999997]的数字中有问题，我们会得到浮点数错误。我有这个问题与JavaScript(谷歌V8和NodeJS)和C (GNU GCC编译器)，所以一个“纯数学”的解决方案是不可能在这里。
基于这个要点和答案，亲爱的用户@Calvintwr
import math
def get_count_digits(number: int):
"""Return number of digits in a number."""
if number == 0:
return 1
number = abs(number)
if number <= 999999999999997:
return math.floor(math.log10(number)) + 1
count = 0
while number:
count += 1
number //= 10
return count
我在长度不超过20(包括20)的数字上进行了测试，没问题。它必须足够，因为64位系统上的最大整数长度是19 (len(str(sys.maxsize)) == 19)。
assert get_count_digits(-99999999999999999999) == 20
assert get_count_digits(-10000000000000000000) == 20
assert get_count_digits(-9999999999999999999) == 19
assert get_count_digits(-1000000000000000000) == 19
assert get_count_digits(-999999999999999999) == 18
assert get_count_digits(-100000000000000000) == 18
assert get_count_digits(-99999999999999999) == 17
assert get_count_digits(-10000000000000000) == 17
assert get_count_digits(-9999999999999999) == 16
assert get_count_digits(-1000000000000000) == 16
assert get_count_digits(-999999999999999) == 15
assert get_count_digits(-100000000000000) == 15
assert get_count_digits(-99999999999999) == 14
assert get_count_digits(-10000000000000) == 14
assert get_count_digits(-9999999999999) == 13
assert get_count_digits(-1000000000000) == 13
assert get_count_digits(-999999999999) == 12
assert get_count_digits(-100000000000) == 12
assert get_count_digits(-99999999999) == 11
assert get_count_digits(-10000000000) == 11
assert get_count_digits(-9999999999) == 10
assert get_count_digits(-1000000000) == 10
assert get_count_digits(-999999999) == 9
assert get_count_digits(-100000000) == 9
assert get_count_digits(-99999999) == 8
assert get_count_digits(-10000000) == 8
assert get_count_digits(-9999999) == 7
assert get_count_digits(-1000000) == 7
assert get_count_digits(-999999) == 6
assert get_count_digits(-100000) == 6
assert get_count_digits(-99999) == 5
assert get_count_digits(-10000) == 5
assert get_count_digits(-9999) == 4
assert get_count_digits(-1000) == 4
assert get_count_digits(-999) == 3
assert get_count_digits(-100) == 3
assert get_count_digits(-99) == 2
assert get_count_digits(-10) == 2
assert get_count_digits(-9) == 1
assert get_count_digits(-1) == 1
assert get_count_digits(0) == 1
assert get_count_digits(1) == 1
assert get_count_digits(9) == 1
assert get_count_digits(10) == 2
assert get_count_digits(99) == 2
assert get_count_digits(100) == 3
assert get_count_digits(999) == 3
assert get_count_digits(1000) == 4
assert get_count_digits(9999) == 4
assert get_count_digits(10000) == 5
assert get_count_digits(99999) == 5
assert get_count_digits(100000) == 6
assert get_count_digits(999999) == 6
assert get_count_digits(1000000) == 7
assert get_count_digits(9999999) == 7
assert get_count_digits(10000000) == 8
assert get_count_digits(99999999) == 8
assert get_count_digits(100000000) == 9
assert get_count_digits(999999999) == 9
assert get_count_digits(1000000000) == 10
assert get_count_digits(9999999999) == 10
assert get_count_digits(10000000000) == 11
assert get_count_digits(99999999999) == 11
assert get_count_digits(100000000000) == 12
assert get_count_digits(999999999999) == 12
assert get_count_digits(1000000000000) == 13
assert get_count_digits(9999999999999) == 13
assert get_count_digits(10000000000000) == 14
assert get_count_digits(99999999999999) == 14
assert get_count_digits(100000000000000) == 15
assert get_count_digits(999999999999999) == 15
assert get_count_digits(1000000000000000) == 16
assert get_count_digits(9999999999999999) == 16
assert get_count_digits(10000000000000000) == 17
assert get_count_digits(99999999999999999) == 17
assert get_count_digits(100000000000000000) == 18
assert get_count_digits(999999999999999999) == 18
assert get_count_digits(1000000000000000000) == 19
assert get_count_digits(9999999999999999999) == 19
assert get_count_digits(10000000000000000000) == 20
assert get_count_digits(99999999999999999999) == 20
所有使用Python 3.5测试的代码示例
好吧，如果不转换为字符串，我会这样做:
def lenDigits(x):
"""
Assumes int(x)
"""
x = abs(x)
if x < 10:
return 1
return 1 + lenDigits(x / 10)
最小递归FTW
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