MACROMEDIA COLDFUSION 5-DEVELOPING Develop Manual page 162

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Backreferences
Backreferencing allows you to match text in previously matched sets of parentheses.
A slash followed by a digit n (\n) refers to the n
One example of how you can use backreferencing is searching for doubled words; for
example, to find instances of 'the the' or 'is is' in text. The following example shows
the syntax you use for backreferencing in regular expressions:
(\b[A-Za-z]+)[ ]+\1
This code matches text that contains a word (specified by the \b word boundary
special character and the [A-Za-z]+) followed by one or more spaces [ ]+, followed by
the first matched subexpression in parentheses. For example, it would match "is is,
or "This is is", but not "This is".
Exact and partial matches
Entered data is normally valid if any of it matches the regular expression pattern.
Often you might want to make sure that the entire entry matches the pattern. If so,
you must "anchor" it to the beginning and end of the field as follows:
A one-character regular expression or grouped subexpression followed by a plus
(+) matches one or more occurrences of the regular expression. For example,
[a-z]+ matches one or more lowercase characters.
A one-character regular expression or grouped subexpression followed by a
question mark (?) matches zero or one occurrences of the regular expression. For
example, xy?z matches either "xyz" or "xz".
The carat (^) at the beginning of a regular expression matches the beginning of
the field.
The dollar sign ($) at the end of a regular expression matches the end of the field.
The concatenation of regular expressions creates a regular expression that
matches the corresponding concatenation of strings. For example, [A-Z][a-z]*
matches any capitalized word.
The OR character (|) allows a choice between two regular expressions. For
example, jell(y|ies) matches either "jelly" or "jellies".
Braces ({}) are used to indicate a range of occurrences of a regular expression, in
the form {m, n} where m is a positive integer equal to or greater than zero
indicating the start of the range and n is equal to or greater than m, indicating the
end of the range. For example, (ba){0,3} matches up to three pairs of the
expression "ba". The form {m,} requires at least m occurrences of the preceding
regular expression. The form {m} requires exactly m occurrences of the preceding
regular expression.The syntax {,n} is not allowed.
If a caret (^) is at the beginning of a pattern, the field must begin with a string that
matches the pattern.
If a dollar sign ($) is at the end of pattern, the field must end with a string that
matches the pattern.
If the expression starts with a caret and ends with a dollar sign, the field must
exactly match the pattern.
Chapter 9 Building Dynamic Forms
th
parenthesized subexpression.