Python float - str - 浮动怪异
it1352
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问题说明
>>> 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.
正确答案
#1
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.
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