Regular Expressions in ColdFusion MX7

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Regular Expressions in ColdFusion MX7

• Seattle CFUG Meeting
• Thursday November 3, 2006
• Presented by Traber Campbell

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What is a regular expression?

• A regular expression (regex) is a string that
  describes or matches a set of strings, according
  to certain syntax rules
• A standard definition for searching and replacing
  text strings works in CF, Java, Perl, php, UNIX
  commands such as grep and awk, and many more!
• An incredibly powerful way to search, replace,
  and parse text

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What can I use it for?

• Validate user input
• Find specific text
• Parse a string
• Replace verb forms
• Add link tags to pages
• Imagine the possibilities!

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Where can I use a regex?

• ltcfparamgt
• IsValid()
• REFind()
• REFindNoCase()
• REReplace()
• REReplaceNoCase()

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Special characters
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CF usage

• ltcfparam namevariable_name typeregex or
  regular_expression patternregular expressiongt
• IsValid("regex" or "regular_expression", value,
  pattern)
• REFind(pattern, string , start ,
  returnsubexpressions )
• REReplace(string, pattern, substring , scope )
• REFindNoCase() and REReplaceNoCase() are
  case-insensitive versions of REFind() and
  REReplace(). The syntax is identical

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ltcfparamgt examples

• Validate from a list
• ltcfparam nameForm.Select typeregex
  pattern(redgreenblue)
• Validate ssn
• ltcfparam nameForm.SSN typeregex
  pattern\d3-\d2-\d4gt

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Syntax (LiveDocs)

• Go to LiveDocs

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Badass CF return subexpressions

• REFind() supports an option called
  returnsubexpressions
• If false (the default), REFind() returns the
  position in the string where the match begins, or
  0 if not found
• If true, REFind() returns a structure that
  contains two arrays, len and pos
• Why is this cool? The returned arrays contain
  the start position and length of EVERY matched
  expression in the string. You can validate and
  parse data in a single expression.

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A few words of caution

• ColdFusion supports the basic regular expression
  syntax
• ColdFusion regular expressions are not 100
  Perl-compatible. Some Perl examples (especially
  more complex ones) may not work in CF.

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More Information

• Macromedia ColdFusion LiveDocs (http//livedocs.ma
  cromedia.com/coldfusion/7/) Regex in CF,
  including syntax and examples.
• Mastering Regular Expressions, Third Edition, by
  Jeffrey E. F. Freidl (OReilly) Everything you
  ever wanted to know about regular expression
• Perl Cookbook, Second Edition By Tom
  Christiansen, Nathan Torkington (OReilly) Perl
  is all about regex. Lots of examples.
• Teach Yourself Regular Expressions in 10 Minutes,
  by Ben Forta obligatory Forta reference ?
• Wikipedia (really) (http//en.wikipedia.org/wiki/R
  egular_expression) Good intro, examples, and
  links
• Regular Expression Library (http//regexlib.com/)
  Why reinvent the wheel?