RegEx Validations

I am new to Reg Expressions. How can I check if a textbox can only h开发者_Go百科old Y,y,N,n values, Textbox 2 can only have string "abc" or "cba" What will be the ValidationExpression? I will really appreciate help. Thank you in advance.

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Your first example:

/[YyNn]/

Your other example:

/(abc|cba)/

I recommend reading about regular expressions here: http://perldoc.perl.org/perlretut.html

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Y|y|N|n for Textbox 1 (abc)|(cba) for Textbox 2

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If you are new to regular expressions, may I recommend this? http://code.google.com/p/kiki-re/

It's a regular expressions tester, you write your regex and some text to text it. It's really nice to learn about regexes and to test them too ;).