"Patty" <pa...@cruzio.com> wrote
for c in 'abcd':
c takes the value of each letter in turn
When I first looked at this - I thought that the variable 'c' would
have had to be initialized first earlier in the program.
It is initialized earluier - in the for statement, each time through
the
loop it gets reinitialized to a new value.
... I wasn't thinking counting variable for some reason. So is
'for c in', one or more of key words that Python understands that a
loop is here and to actually trigger counting in a loop? Does it
start with a 1 or 0 internally to do this?
In the case of a for loop it doesn't count as such.
It takes each value from a sequience and applies it to the
loop variable. Personally I think it wouyld have read better
if they called it "foreach" so your loop would look like
foreach char in 'abcd':
or
foreach item in [1,2,3,4]:
etc...
But they didn't so we are stuck with for.
I also realized a mistake I may have made - maybe I confused 'for c
in'
while c in 'abcd':
This is completely different.
In this case we can clarify it by adding some parentheses:
while (c in 'abcd'):
the test is all of the bit in parens. And the test is a test of
whether
c is in the string or not. Python does not modify the variable 'c' in
this case, that only happens with a for loop.
You can read more about the various python loop structures
in the loops topic of my tutorial.
--
Alan Gauld
Author of the Learn to Program web site
http://www.alan-g.me.uk/
_______________________________________________
Tutor maillist - Tutor@python.org
To unsubscribe or change subscription options:
http://mail.python.org/mailman/listinfo/tutor
