while loop - multiple condition

[Denis McMahon]

On Sun, 12 Oct 2014 17:08:00 +0000, Shiva wrote:

> while ans.lower() != 'yes' or ans.lower()[0] != 'y':

while ans.lower() is not equal to "yes"
   or ans.lower()[0] is not equal to "y"

the loop will continue to run

Note that if ans.lower() == 'y', then the first clause ( ans.lower() != 
'yes' ) is true, so the loop will continue to run, ignoring the result of 
the second clause ( ans.lower()[0] != 'y' ), This will also be the case 
if you reverse the order of the clauses.

It seems that you need a better understanding of combinatorial logic, 
perhaps http://www.ee.surrey.ac.uk/Projects/Labview/boolalgebra/
index.html#booleantheorems will help.

-- 
Denis McMahon, denismfmcmahon at gmail.com