问题描述
>>> float(str(0.65000000000000002)) 0.65000000000000002 >>> float(str(0.47000000000000003)) 0.46999999999999997 ???
这里发生了什么?如何将 0.47000000000000003 转换为字符串并将结果值转换回浮点数?
What is going on here? How do I convert 0.47000000000000003 to string and the resultant value back to float?
我在 Windows 上使用 Python 2.5.4.
I am using Python 2.5.4 on Windows.
推荐答案
str(0.47000000000000003) 给 '0.47' 和 float('0.47') 可以是 0.46999999999999997.这是由于浮点数的表示方式(参见这篇 wikipedia 文章)
str(0.47000000000000003) give '0.47' and float('0.47') can be 0.46999999999999997. This is due to the way floating point number are represented (see this wikipedia article)
注意:float(repr(0.47000000000000003)) 或 eval(repr(0.47000000000000003)) 会给你预期的结果,但你应该使用 十进制,如果你需要精确的话.
Note: float(repr(0.47000000000000003)) or eval(repr(0.47000000000000003)) will give you the expected result, but you should use Decimal if you need precision.