Greetings, Kaushal: There are two topics to understand here:
1. what "TRUE" and "FALSE" mean in Python, and 2. how Python evaluates "X and Y". The tutorial "Instant Python" by Magnus Lie Hetland has good, short descriptions of these two topics, so I'll borrow from it. You can find the document at: http://www.hetland.org/python/instant-python.php 1. "All values in Python can be used as logic values. Some of the more "empty" ones, like [], 0, "" and None represent logical falsity, while most other values (like [0], 1 or "Hello, world") represent logical truth." In your examples, 5 and 1 are both considered 'TRUE', while 0, of course, is considered "FALSE". 2. "Now, logical expressions like a and b are evaluated like this: First, check if a is true. If it is not, then simply return it. If it is, then simply return b (which will represent the truth value of the expression.) The corresponding logic for a or b is: If a is true, then return it. If it isn't, then return b." Python evaluates your example expressions like this: a. Get the first sub-expression. x Get the value of x. 5 Is 5 a "TRUE" value? Yes Since the operator is "and", get the second sub-expression. 1 Is 1 a "TRUE" value? Yes Return it. 1 b. Get the first sub-expression. y Get the value of y. 0 Is 0 a "TRUE" value? No Since the operator is "and", STOP and return the sub-expression. 0 Does this help? Try this: change the 'and' operator in your examples to 'or'. What would the return value be now? 5 or 1 = ??? 0 or 1 = ??? Regards, Barry [EMAIL PROTECTED] 541-302-1107 ________________________ We who cut mere stones must always be envisioning cathedrals. -Quarry worker's creed > -----Original Message----- > Date: Thu, 6 Apr 2006 16:06:11 +0530 > From: "Kaushal Shriyan" <[EMAIL PROTECTED]> > Subject: [Tutor] Logical Operators > To: tutor@python.org > Message-ID: > <[EMAIL PROTECTED]> > Content-Type: text/plain; charset=ISO-8859-1 > > Hi > > I am referring to http://www.ibiblio.org/obp/thinkCSpy/chap04.htm > about Logical operators > > I didnot understood > > >>> x = 5 > >>> x and 1 > 1 > >>> y = 0 > >>> y and 1 > 0 > > How 5 and 1 means 1 and 0 and 1 means 0 > > Thanks > > Regards > > Kaushal _______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
