my $string = "ABCDEFGHIJKLMNOPCDEFQRST";
my $find = "CDEF";

if( $string =~ /$find/ ){
  print "found $find in $string\n";
}
# OR
my $index = index( $string, $find );
if( $index > 0 ){
  print "found $find in $string at position $index\n";
}

##</code><code>##

s**lil*;  $*=join'',sort split q**;  s;.*;grr; &&s+(.(.)).+$2$1+; $; =
qq-$_-;s,.*,ahc,;$,.=chop for split q,,,reverse;print for($,,$;,$*,$/)