Truth value of a string in python -
if <boolean> : # boolean has either true or false.
then why
if "poi": print "yes" output: yes
i didn't why yes printing , since "poi" nether true or false.
python best evaluate "truthiness" of expression when boolean value needed expression.
the rule strings empty string considered false, non-empty string considered true. same rule imposed on other containers, empty dictionary or list considered false, dictionary or list 1 or more entries considered true.
the none object considered false.
a numerical value of 0 considered false (although string value of '0' considered true).
all other expressions considered true.
details (including how user-defined types can specify truthiness) can found here: http://docs.python.org/release/2.5.2/lib/truth.html.
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