$len
From Scriptwiki
Returns the length of a string, i.e. how many characters are within it.
$len(text)
$len() is a simple, but powerful tool for processing strings.
Examples
$len(test string) returns 11.
The following example turns uppercase letters to lowercase and vice-versa.
$len is used to get the length of the string (the value given to the alias) and loop through its every character.
alias changecase { var %i = 1, %str, %c while (%i <= $len($$1-)) { %c = $mid($1-, %i, 1) if ($isupper(%c)) { %str = %str $+ $lower(%c) } else { %str = %str $+ $upper(%c) } inc %i } return %str } echo -a $changecase(Hello) ; returns hELLO