sre_constants.error: bogus escape

[Jeff Epler]

On Tue, Nov 05, 2002 at 01:25:19PM -0600, Bradley D. Larson wrote:
> What is the best method of changing a \ character to something else
> 
> I'm trying to use re....
> 
>         pat = re.compile('\\');  ts = pat.sub(':',ts)
> 
> which produces....
> 
>   File "C:\PYTHON21\Lib\sre.py", line 90, in compile
>     return _compile(pattern, flags)
>   File "C:\PYTHON21\Lib\sre.py", line 136, in _compile
>     raise error, v # invalid expression
> sre_constants.error: bogus escape
> 
> 

It is bogus.  If you want to match a literal backslash, the regular
expression '\\\\', also writable as r'\\' is what you're looking for.
'\\' (a 1-character string containing a single backslash) is not a valid
regular expression, much as '%' (a 1-character string containing a single
percent sign) is not a valid format string (i.e., don't try to do "%" %
(...))

Jeff