How is the logical processing being done for strings like 'Dog' and 'Cat'
timr at probo.com
Tue Oct 21 06:02:43 CEST 2008
Sumitava Mukherjee <smukh at cognobytes.com> wrote:
>I am a novice programmer in Python.
>Please could you explain me the results (regarding logical operators).
>I get this:
>>>> print bool('God' and 'Devil')
>[This is ok because (any) string is True, so; (True and True) gives
Your statement is accurate, but that's not why it returns true.
>>>> print('God' and 'Devil')
Right. And bool('Devil') is True, because a non-empty string is a true
>[This is what I don't get ]
>and for that matter,I also checked out this:
>>>> 01 and 10
>What is python doing when we type in ('God' and 'Devil') or key in (01
>and 10) ?
"and" and "or" are a bit more than logical operators. The exact definition
of "x and y" is "if x has a false value, return x, otherwise return y". If
both sides are booleans, this does exactly what you expect.
Similarly, "x or y" is actually done as "if x has a true value, return x,
otherwise return y".
This allows for one of the cuter Python hacks:
xxx = x and y or z
which is essentially the same as the C ternary operator:
xxx = x ? y : z;
Tim Roberts, timr at probo.com
Providenza & Boekelheide, Inc.
More information about the Python-list