string stripping issues

Ben Cartwright bencvt at gmail.com
Thu Mar 2 23:15:17 CET 2006


Ben Cartwright wrote:
> orangeDinosaur wrote:
> > I am encountering a behavior I can think of reason for.  Sometimes,
> > when I use the .strip module for strings, it takes away more than what
> > I've specified.  For example:
> >
> > >>> a = '    <TD WIDTH=175><FONT SIZE=2>Hughes. John</FONT></TD>\r\n'
> >
> > >>> a.strip('    <TD WIDTH=175><FONT SIZE=2>')
> >
> > returns:
> >
> > 'ughes. John</FONT></TD>\r\n'
> >
> > However, if I take another string, for example:
> >
> > >>> b = '    <TD WIDTH=175><FONT SIZE=2>Kim, Dong-Hyun</FONT></TD>\r\n'
> >
> > >>> b.strip('    <TD WIDTH=175><FONT SIZE=2>')
> >
> > returns:
> >
> > 'Kim, Dong-Hyun</FONT></TD>\r\n'
> >
> > I don't understand why in one case it eats up the 'H' but in the next
> > case it leaves the 'K' alone.
>
>
> That method... I do not think it means what you think it means.  The
> argument to str.strip is a *set* of characters, e.g.:
>
>   >>> foo = 'abababaXabbaXabababbbb'
>   >>> foo.strip('ab')
>   'XabbaX'
>   >>> foo.strip('aabababaab') # no difference!
>   'XabbaX'
>
> For more info, see the string method docs:
> http://docs.python.org/lib/string-methods.html
> To do what you're trying to do, try this:
>
>   >>> prefix = 'hello '
>   >>> bar = 'hello world!'
>   >>> if bar.startswith(prefix): bar = bar[:len(prefix)]
>   ...
>   >>> bar
>   'world!'


Apologies, that should be:
   >>> prefix = 'hello '
   >>> bar = 'hello world!'
   >>> if bar.startswith(prefix): bar = bar[len(prefix):]
   ...
   >>> bar
   'world!'

--Ben




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