Question

This is an example that searches PDF files in the current directory.

import os, os.path
import re

def print_pdf (arg, dir, files):
 for file in files:
  path = os.path.join(dir, file)
  path = os.path.normcase(path)
  if re.search(r".*\.pdf", path):
   print path

os.path.walk('.', print_pdf, 0)

Could anyone explain what r".*\.pdf" means here?

Why ".*\"?

Thanks!

Answer 1

Why ".*\"?

Wrong question, you missed a crucial character of the expression. 😉

In fact, .* will match any character (. in regex), as many times as possible (* in regex; relates to the previous string, so . in this case).

\., on the other hand, will match exactly one dot (.). \ escapes the following character (.) so it does no longer have its special meaning (e.g. in this case “match any character”) but rather it will be treated as-is.