Python十进制.InvalidOperation错误 [英] Python decimal.InvalidOperation error

问题描述

运行以下命令时，我总是会收到此错误:

i'm always getting this error when running something like this:

from decimal import *
getcontext().prec =30

b=("2/3")

Decimal(b)

错误:

Traceback (most recent call last):
  File "Test.py", line 6, in <module>
    Decimal(b)
decimal.InvalidOperation: [<class 'decimal.ConversionSyntax'>]

此外，为什么我要从控制台获得此结果?

Also, why do i get this result from the console?

>>> Decimal(2/3)
Decimal('0.66666666666666662965923251249478198587894439697265625')

谢谢

推荐答案

Decimal的初始化程序不能接受带斜杠的字符串.非正式地，字符串必须看起来像单个数字. 此表显示了字符串参数的正确格式.如果要计算2/3，请执行

Decimal's initializer can't accept strings with a slash in them. Informally, the string has to look like a single number. This table shows the proper format for string arguments. If you want to calculate 2/3, do

>>> Decimal(2)/Decimal(3)
Decimal('0.6666666666666666666666666667')

Decimal(2/3)给出Decimal('0.66666666666666662965923251249478198587894439697265625')的原因是2/3计算为浮点数，并且浮点数固有地具有有限的精度.这是计算机最接近使用浮点数表示2/3的地方.

Decimal(2/3) gives Decimal('0.66666666666666662965923251249478198587894439697265625') because 2/3 evaluates to a floating point number, and floats have inherently limited precision. That's the closest the computer can get to representing 2/3 using a float.

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