A valid DNS name has to be (it does not have to have .com etc.)
1. A host name (label) can start or end with a letter or a number
2. A host name (label) MUST NOT start or end with a '-' (dash)
3. A host name (label) MUST NOT consist of all numeric values
4. A host name (label) can be up to 63 characters
I am new to perl. Can you write either one or 4 separate regular expression (i prefer multiple regex)?
A year or so back I was asked to have a play with MongoDB; within half an hour I had downloaded (http://www.mongodb.org/downloads), installed and started the daemon, and had a console window open.
After an hour or two of playing at the command …
Learn how to match and substitute tagged data using PHP regular expressions. Demonstrated on Windows 7, but also applies to other operating systems. Demonstrated technique applies to PHP (all versions) and Firefox, but very similar techniques will w…
Explain concepts important to validation of email addresses with regular expressions. Applies to most languages/tools that uses regular expressions.
Consider email address RFCs:
Look at HTML5 form input element (with type=email) regex pattern: