print $str."\n<br />";
  if ( ($str =~ /\\r/) or ($str =~ /\\n/) or ($str =~ /\\f/) or ($str =~ /\\t/) ) { ##0
    print "found ws using multiple regexps and or with double backslashes\n<br />";
  }
  if ($str =~ /\\r|\\n|\\t|\\f/) { print "matches on ws using simple '|' list with double backslashes\n<br />";} ## 1
  if ($str =~ /[\\r,\\n,\\t,\\f]/) { print "matches in character  class\n<br />";} ##2
  if ($str =~ /\r|\n|\t|\f/) { print "matches on single backslash\n<br />";} ##3
  if ( ($str =~ /\\n/) ) { print "matches \\\\n (with double backslash)\n<br />";} ##4
  if ($str =~/\s/) { print "matches on \\s  \n<br />";}##5


##</code><code>##

rrrrrrrrrr
matches in character class 

##</code><code>##

rrrrrrrr\nrr
found ws using multiple regexps and or with double backslashes
matches on ws using simple '|' list with double backslashes
matches in character class
matches \\n (with double backslash) 

##</code><code>##

rrrrrrrr\rr
found ws using multiple regexps and or with double backslashes
matches on ws using simple '|' list with double backslashes
matches in character class