[ ]—Characters in set. [ ] matches a string that contains only the characters specified between the brackets. Character matches are case sensitive. The [ ] conversion code is useful only when you are scanning strings. To match the caret symbol (^) in a set, make sure it is not the first character after the bracket. The following examples demonstrate the use of the characters in set conversion code:
%[aeiou]—Matches any string that contains only lowercase vowels.
%[0-9a-zA-Z ]—Matches a string that contains numbers, letters, or spaces. You can use a hyphen to specify ranges of characters in the set.
%[^,;]—Matches any string of characters up to but not including the first comma or semicolon.
If the parameter represented by Hello can also contain a %, then use "Match Pattern" or "Match Regular Expression" instead to allow backtracking.