Jim Duffy is founder and president of Take Note Technologies, an award-winning training, consulting, and software development company specializing in . Jim is a Microsoft Regional Director, a Microsoft MVP, an ASPInsider, and is an entertaining and popular speaker at regional user groups and international developer conferences.
NET software developer training and helping clients create business solutions with Microsoft enterprise technologies. You can find additional information about Jim, Take Note Technologies, links to his blog, as well as a public training class schedule, on-site training information, consulting information, and software development services at expressions, also referred to as "regex" in the developer community, is an extremely powerful tool used in pattern matching and substitution. The name doesn't conjure up any grandiose ideas about what they are all about. For those of you who struggled to learn how to use them, you're probably thinking they should be renamed irregular expressions.
That's why you needed the ^ in the beginning and the $ on the end to define the beginning and ending structure of the pattern.You now know that this pattern defines a 4-character string with two initial letters followed by two ending digits.This will cause anything to be matched EXCEPT what is specified.This expression will match 6take Note and ztake Note but will not match a similar string like 4take Note because it starts with a 4, or 5takenote because the "n" in note is not capitalized.One thing to watch out for is making sure you don't subconsciously read the as a concatenation operator. What if you need to match a string that contains one of the metacharacters, "? One thing to watch out for is making sure you don't subconsciously read the as a concatenation operator. The * matches 0 or more instances of the preceding character. except that it matches 0 or more instances of the preceding character whereas the ? Social Security numbers but they do match the pattern.
only matches 0 or 1 instances of the preceding character. This pattern will match a date in the 99/99/9999 format.
He is an energetic trainer, skilled developer, and has been published in leading developer-oriented publications.
He has a BS degree in Computer and Information Systems and over 25 years of programming and training experience.
In this type of situation, you might use a regular expression to determine whether the "From:" e-mail address is the e-mail address of a known spammer.
As a matter of fact, many e-mail filtering programs use regular expressions for exactly this reason.
What if the pattern called for four characters followed by six digits? Luckily there is regular expression notation for that type of character repetition. matches 0 or 1 instances of the preceding character.