Greetings O Wise Ones

I'm having a problem getting a good regular expression for this problem

For any given string, I would like to match on a string contains the sequence of characters "\n","\f","\t" or "\r" e.g. match on $str = "Test\n" but not on $str = "Test".

So my code looks like this ...

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

and I get the following results

rrrrrrrrrr
matches in character class
[download]

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)
[download]

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
[download]

Regexp 0 and 1 appear to work but is there a better or more succint way to do it?

My 'character class' regexp 2, doesn't work. It matches on a plain 'r'. I've obviously go tsomething wrong here but I have no idea what. If anyone can enlighten me I'd be glad to learn.

I believe regexp 3, with single backslashes doesn't work because it is looking for an actual whitespace character such as 0x0a or 0x0d and not a character string representing a whitespace character

Regexp 4 isn't really completing the task so it doesn't appear when I use \r but does when I use \n.

I think regexp 5 fails for the same reasons regexp No 3 fails

Is there a character class to deal with this regexp problem and/or a more succint way of expressing the regexp?