Python float - str - 漂浮奇怪 [英] Python float - str - float weirdness
问题描述
>>> float(str(0.65000000000000002))
0.65000000000000002
>>> float(str(0.47000000000000003))
0.46999999999999997 ???
这是怎么回事?
如何将 0.47000000000000003
转换为字符串,并将结果值转换为浮点数?
Python 2.5.4在Windows上。
str(0.47000000000000003)
give '0.47'
和 float('0.47')
可以是 0.46999999999999997
。
这是由于浮点数的表示方式(见维基百科文章)注意: float(repr(0.47000000000000003))
或者 eval(repr(0.47000000000000003)) )
会给你预期的结果,但你应该使用 Decimal 如果你需要精确度。
>>> float(str(0.65000000000000002))
0.65000000000000002
>>> float(str(0.47000000000000003))
0.46999999999999997 ???
What is going on here?
How do I convert 0.47000000000000003
to string and the resultant value back to float?
I am using Python 2.5.4 on Windows.
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)
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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