[Tutor] why does this fail

[Roelof Wobben]

> Date: Wed, 25 Aug 2010 12:27:39 +0200
> From: cwitts at compuscan.co.za
> To: tutor at python.org
> Subject: Re: [Tutor] why does this fail
> 
> On 25/08/2010 12:00, Roelof Wobben wrote:
> > Hello,
> >
> > I have this programm :
> >
> > def remove_letter(letter, strng):
> > """
> > >>> remove_letter('a', 'apple')
> > 'pple'
> > >>> remove_letter('a', 'banana')
> > 'bnn'
> > >>> remove_letter('z', 'banana')
> > 'banana'
> > >>> remove_letter('i', 'Mississippi')
> > 'Msssspp'
> > """
> > antwoord=""
> > for letter in strng:
> > print letter, strng
> > if letter in strng:
> > print "false"
> > else:
> > print "true"
> > return antwoord
> >
> > x=remove_letter('a', 'apple')
> > print x
> >
> > But now everything is false even a in apple.
> >
> > What is here wrong ?
> >
> > Roelof
> >
> >
> > _______________________________________________
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> 
> You're rebinding the variable `letter`.
> It is an input variable for your function but then you use it as the 
> character store while iterating through your string variable `strng`.
> 
> What your control should look like would be more like
> 
> for character in strng:
> if letter == character:
> print 'false' # this should be true, it is a match just like in 
> your example
> else:
> print 'true'
> 
> I'm assuming this function is just for learning purposes because there's 
> a built-in string function you can use called replace and you'd use it 
> as such `'apple'.replace('a', '')`.
> 
> PS: Once you've gotten it to work convert it to a list comprehension, 
> they are incredibly useful and a great tool.
> 
> -- 
> Kind Regards,
> Christian Witts
> 
> 
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Hello Christian.
 
It's for learning purposed but I forget that de module string has built in functions.
Thank you for remainding it to me.
 
list comprehistion is q few chapters later in the book so I don't try yet.
 
Roelof
 		 	   		  
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