Regular expression to match a #

[John Machin]

Tom Deco wrote:
> Hi,
> 
> I'm trying to use a regular expression to match a string containing a #
> (basically i'm looking for #include ...)
> 
> I don't seem to manage to write a regular expression that matches this.
> 
> My (probably to naive) approach is: p = re.compile(r'\b#include\b)
> I also tried p = re.compile(r'\b\#include\b) in a futile attempt to use
> a backslash as escape character before the #
> None of the above return a match for a string like "#include <stdio>".
> 
> I know a # is used for comments, hence my attempt to escape it...
> 
> Any suggestion on how to get a regular expression to find a #?
> 
> Thanks
> 

You definitely shouldn't have the first \b -- match() works only at the 
beginning of the target string, so it is impossible for there to be a 
word boundary just before the "#".

You probably shouldn't have the second \b.

You probably should read section A12 of K&R2.

You probably should be using a parser, but if you persist in using 
regular expressions:

(a) read the manual.

(b) try something like this:

 >>> pat1 = re.compile(r'\s*#\s*include\s*<\s*([^>\s]+)\s*>\s*$')
 >>> pat1.match("   # include <   fubar.h   >   ").group(1)
'fubar.h'

N.B. this is based the assumption that sane programmers don't have 
whitespace embedded in the names of source files ;-)

HTH,
John