On 5 July 2010 12:53, Richard D. Moores <rdmoo...@gmail.com> wrote: > On Mon, Jul 5, 2010 at 04:09, Stefan Behnel <stefan...@behnel.de> wrote: > > Richard D. Moores, 05.07.2010 11:37: > >> > >> I keep getting hung up over the meaning of "the return > >> value" of an expression. I am of course familiar with values returned > >> by a function, but don't quite grasp what the return value of, say, > >> the y of "x and y" might mean. > > > > Think of a different expression, like "1+1". Here, the return value (or > > maybe a better wording would be the result value) is 2. > > > > > >> Also, you distinguish between a return value of True and and the value > >> of y being such (say 5, and not 0) that it makes y true (but not > >> True). So another thing I need to know is the difference between True > >> and true. Also between False and false. And why the difference is > >> important. > > > > "True" is the value "True" in Python, which is a singleton. You can test > for > > it by using > > > > x is True > > Ah. But could you give me an x that would satisfy that? I can think of > > >>> (5 > 4) is True > True > > But how can (5 > 4) be an x? Could you show me some code where it could be? > > >>> x = (5 > 4) > >>> x > True > >>> x is True > True > > So it can! That surprised me. I was expecting "x = (5 > 4)" to be > absurd -- raise an exception? Still seems pretty weird. >
Greater than (>) works like the mathematical operators in returning a value, it just happens that for comparison operators (>, <, ==, !=) the values can only be True or False. HTH, Adam.
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