Chapter 3-Lesson 1

• Regex class is used to match a string against a Regular Expression.
• When validating input, one must put the leading carat ( ^ ) to represent beginning of input and dollar ($) sign to represent end of input pattern so as to minimize the risk of human error.
• The carat (^) would match the expression at the beginning of any line in a multi-line string.
• Regular Expressions characters are case sensitive, even in VB.NET
• Tip: Use Verbatim strings (that begin with @ sign) to create regular expressions to avoid problems with back-slashes.
• Try to learn a few simple Regular Expressions for exam.
• Asterisk (*) means the preceding character must be present zero or more time, while plus (+) sign represents 1 or more times.
• To define a certain number of occurrence for a character use {n} notation after the character where n is the number of occurrences.
• We can also define min-max range for a character using {min,max} notation. We can also leave either as blank.
• Use question mark to make character optional. And Period (.) to represent reserved space for a single character.
• Use Table 3-3 in the MS Press book for further information.
• We may use Back-Referencing (using \k with a named group) to search for repeating characters or groups of characters.
• Use of RegexOptions.ECMAScript with any other options throws an Exception.