The Book of Ruby

Prematch and Postmatch

The MatchData class supplies the pre_match and post_match methods to return the strings preceding or following a match. Here, for example, I am making a match on the comment character, #:

pre_post_match.rb

x = /#/.match( 'def myMethod # This is a very nice method' )
puts( x.pre_match )        #=> def myMethod
puts( x.post_match )       #=>  This is a very nice method

Alternatively, you can use the special variables, $` (with a backquote) and $' (with a normal quote), to access pre- and postmatches, respectively:

x = /#/.match( 'def myMethod # This is a very nice method' )
puts( $` )                 #=> def myMethod
puts( $' )                 #=>  This is a very nice method

When using match with groups, you can use array-style indexing to obtain specific items. Index 0 is ...