[regex] Basic rewriting

[Tim Chase]

> 	I've been reading tutorials on regexes in Python, but I still
> don't get it:
> 
> ========
> #!/usr/bin/python
> 
> #myscript.py 0123456789
> 
> import sys,re
> 
> #Turn 0123456789 into 01.23.45.67.89
> p = re.compile('(\d\d)(\d\d)(\d\d)(\d\d)(\d\d)')
> phone = p.sub('\1.\2.\3.\4.\5',sys.argv[1])
> print phone
> ========
> 
> => Python displays "...." instead. Any idea what I'm doing wrong?


Looks like you need to use "raw" strings of the form

  r'...'

Otherwise, you'd need to escape every backslash so that the
regexp parser actually gets it.  Thus you can either do this:

 p = re.compile(r'(\d\d)(\d\d)(\d\d)(\d\d)(\d\d)')
 phone = p.sub(r'\1.\2.\3.\4.\5',sys.argv[1])

or the much more hideous:

 p = re.compile('(\\d\\d)(\\d\\d)(\\d\\d)(\\d\\d)(\\d\\d)')
 phone = p.sub('\\1.\\2.\\3.\\4.\\5',sys.argv[1])

HTH,

-tkc