Dear List, HOW would do I extract a complete sentence from a text. I have the following codes to extract the concordance lines based on the search term.But it extracts the line with search term in between sentences.The following are the codes:

open INPUT, "< $filename" or die "Cannot open $filename for input:
   $!";

     @text = <INPUT>;
     close (INPUT);
     $text = "@text";

    @splittext = split(/$string/,$text);

 #To extract concordance lines from text
    for (my $i=1; $i < @splittext; $i++)
         {
           my $before = substr((' 'x10).$splittext[$i-1],-20,20);
           my $after = substr($splittext[$i].' 'x10,0,20);
           print p($before, strong($string), $after,"\n"),
      }
[download]

How do I extract the complete sentences from a text like the following :

I came across this before.
I came down from Canada. 
I came back yesterday.
[download]

Thanx,