agreed, I also wasted time answering another question. :(

> Check if a variable contains only one letter

  DB<106> $str='A B C'
 => "A B C"

  DB<107> @matches= $str=~/([A-Z])/g
 => ("A", "B", "C")

  DB<108> scalar @matches
 => 3
[download]

  DB<115> $str='A B C'
 => "A B C"

  DB<116> $str !~ /[A-Z].*[A-Z]/
 => ""

  DB<117> $str="   A   "
 => "   A   "

  DB<118> $str !~ /[A-Z].*[A-Z]/
 => 1
[download]