Ricardo Aráoz wrote: > >>> 1 == True > True Yes, True is an integer with value 1. Actually True is a bool but bool is a subclass of int: In [3]: type(True) Out[3]: <type 'bool'> In [4]: isinstance(True, int) Out[4]: True In [5]: int(True) Out[5]: 1
> >>> 5 == True > False Right, because 5 != 1 > and yet > > >>> if 5 : print 'True' > True > > > I thought a non-zero or non-empty was evaluated as True. Yes, in a boolean context 5 is evaluated as True: In [7]: bool(5) Out[7]: True From the docs: 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. http://docs.python.org/ref/Booleans.html#Booleans Now in the 5 == > True line I'm not saying "5 is True", shouldn't it evaluate just like > the "if" statement? No. When you say if 5: you are implicitly converting 5 to a boolean and the 'non-zero evaluates to True' rule applies. When you say if 5 == True: you are explicitly comparing the two values and 5 is not converted to boolean. From the docs: The operators <, >, ==, >=, <=, and != compare the values of two objects. The objects need not have the same type. If both are numbers, they are converted to a common type. http://docs.python.org/ref/comparisons.html The first one is equivalent to if bool(5): while the second one is if 5 == int(True): Kent _______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
