On Saturday, October 2, 2021 at 4:59:54 PM UTC+8, ju...@diegidio.name wrote: > On Saturday, 2 October 2021 at 10:34:27 UTC+2, hongy...@gmail.com wrote: > > See the following testings: > > > > In [24]: a=3.1415926535897932384626433832795028841971 > > In [27]: -a > > Out[27]: -3.141592653589793 > You've never heard of floating-point? Double precision has 53 significant > bits of mantissa, corresponding approximately to 16 decimal digits. > <https://en.wikipedia.org/wiki/Double-precision_floating-point_format#IEEE_754_double-precision_binary_floating-point_format:_binary64> > > In [17]: ~-+1 > > Out[17]: 0 > << The unary ~ (invert) operator yields the bitwise inversion of its integer > argument. The bitwise inversion of x is defined as -(x+1). It only applies to > integral numbers or to custom objects that override the __invert__() special > method. >> > <https://docs.python.org/3/reference/expressions.html#unary-arithmetic-and-bitwise-operations> > > I'm very puzzled by these operators. Any hints will be highly appreciated. > Try and read the proverbial manual: that's truly a fundamental skill...
Thank you for your explanation. Then what about the following questions?: 1. Should `+' and `-' be classified as binary operators or unary operators? As we all know, `a + b', and `a - b' are the normal ways we do basic arithmetic operations. 2. See the following testings: In [20]: bool(int(True)) Out[20]: True In [21]: bool(~int(True)) Out[21]: True In [22]: bool(~~int(True)) Out[22]: True In [23]: bool(~~~int(True)) Out[23]: True In [24]: bool(int(False)) Out[24]: False In [25]: bool(~int(False)) Out[25]: True In [26]: bool(~~int(False)) Out[26]: False In [27]: bool(~~~int(False)) Out[27]: True Why can’t/shouldn't we get something similar results for both `True' and `False' in the above testings? HZ -- https://mail.python.org/mailman/listinfo/python-list
