Alan Gauld wrote: >> What values represent true in Python? >> > > True > > Its a built-in boolean type value. > > But empty strings, lists, tuples etc are considered False > Similarly zero and None are considered False > Let us be precise here. Empty things are considered False when used where a boolean value is expected. In the language reference, under the if statement I quote:"It selects exactly one of the suites by evaluating the expressions one by one until one is found to be true (see section 5.10 <Booleans.html#Booleans> for the definition of true and false)"
5:10: "In the context of Boolean operations, and also when expressions are used by control flow statements, the following values are interpreted as false: |False|, |None|, numeric zero of all types, and empty strings and containers (including strings, tuples, lists, dictionaries, sets and frozensets). All other values are interpreted as true." The 2 flow control statements that use expressions in this way are if and while. Boolean operations are or, and, not. So in "if [1]: print 1" [1] will be interpreted as True. However in "[1] == True" it will NOT be interpreted as True. -- Bob Gailer 510-978-4454 _______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
