[Tutor] basic problem

[Alan Gauld]

On 06/10/11 23:11, ADRIAN KELLY wrote:

> can someone spell out to me in (simply if possible) what this programme
> is doing.

Mac has done that pretty well.

However, let me add a couple of comments:

> # this programme will adding something to everything the user
> #types by using a for loop

This comment does not describe what the program actually does.
In  fact the program simply echoes what the user types in.
Well. Ok I suppose it adds a space at the front, but it goes
about it in a very long winded way!

> #set values
> new_message=" "
> VOWELS="AEIOU"
> message=raw_input ("Enter a message: ")
> for letter in message:
> if letter.lower() not in VOWELS:
>     new_message = new_message+letter
>     print new_message

In Python = is not a test or statement as it is in math.
For that we use ==. A single = sign is an assignment.

So

x = 42 		means that x takes on the value 42.
x = 42 + 1	means x takes on the value 42+1, or 43

(Some other languages use another symbol for this which in my opinion is 
better, but sadly Python doesn't )

So

      new_message = new_message+letter

means new_message becomes the old value of new_message plus the value of 
letter(which changes on each cycle through the for loop)

This is such a common idiom that, as Mac said, Python provides a 
shorthand way of expressing it:

new_message += letter

HTH,

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/