Python+Regular Expression

By using Regular Expression we embed it into python-script and provide some string literals insearch of any pattern match with files.

Here we can question like "does the given string match with the pattern?"

Matching Characters

   '.'         Matches any character except a newline

   '^'                  Matches the start of the string

   '$'                  Matches the end of the string /  before the newline

   '*'                  eg: ha* will match ‘h’, ‘ha’, or ‘h’ followed by any number of   ‘a’s.

   '+'                  eg: ha+ will match ‘h’ followed by any non-zero number of ‘a’s

   '?'

*?, +?, ?? greedy match.where +,?,* looks for all possible matches of string  in entire text given.

   {m}    eg: a{6}will match  six 'a' characters not less than it

   {m,n}   eg: a{3,5} will match from 3 to 5 'a' characters.

   '\'      Escapes special characters ('*', '?').

   []     Indicate a set of characters  in a set:

     e.g. [amk] will match 'a', 'm', or 'k'