Alex Young wrote:
> http://ruby-doc.org/core/classes/String.html#M001849 says this:
>
>   "cat o' 9 tails" =~ '\d'   #=> nil
>
> I get this:
>
> irb(main):001:0> "cat o' 9 tails" =~ '\d'
> TypeError: type mismatch: String given
>         from (irb):1:in `=~'
>         from (irb):1
>
> $ ruby -v
> ruby 1.8.4 (2005-12-24) [i386-mswin32]
>
> Any clues?
>
Use a regexp:

irb(main):004:0> "cat o' 9 tails" =~ /\d/
=> 7