Friday, November 21, 2008

Regular Expressions

In the resent past I had to write some simple regular expressions.
So thought of sharing them with you.

An EMail Address Validator

^([a-zA-Z0-9_\-\.]+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)(([a-zA-Z0-9\-]+\.)+))([a-zA-Z]{2,4}[0-9]{1,3})(\]?)$
This will validate the entered EMail address.

A Password Validator

(?=.{6,})[a-zA-Z]+[^a-zA-Z]+[^a-zA-Z]+[a-zA-Z]+
This will validate the password to have at least 1 alphabetic character and 1 numeric digit, and altogether the password will be more than 6 characters long.

A Telephone Number Valdator

\d{4}\s\d{3}\s\d{6}
This will expect the telephone number to be in international format. For example (0094 777 123456).

A Simple Length Validator

[\s\S]{1,200}
This will allow only only 200 or lesser characters for input.


A Length Validator Which Works With Linefeed (Return, Enter)

^(.\n){0,500}$
This will validate and allow only 500 input even in a multi line field when linefeed (enter) is used in between.

A Date Validator

(0[1-9]1[012])[- /.](0[1-9][12][0-9]3[01])[- /.](1920)\d\d

This will check for the date validness. The date format should be mm/dd/yyyy to correctly validate by this.

If the date format is required as yyyy/mm/dd then use the following.

(1920)\d\d[- /.](0[1-9]1[012])[- /.](0[1-9][12][0-9]3[01])

Following are some good sites that you can refer for regular expression help.

http://www.visibone.com/regular-expressions/

http://books.google.lk/books?hl=en&id=NYEX-Q9evKoC&dq=Regular+expressions&printsec=frontcover&source=web&ots=qok1lUQubw&sig=XVd8_Z3hM_CWqk5r9dupyAWIllk&sa=X&oi=book_result&resnum=6&ct=result#PPP1,M1

http://regexlib.com/CheatSheet.aspx

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