Question

How can I make a regular expression that would say the following:

FirstName.LastName or FirstName.Letter.LastName

To allow example:

• John.Smith
• John.S.Smith

Not to allow example:

• John Smith
• John
• John.
• John.Smi th
• John.S.D.Smith

Thanks in advance!

Greg

Answer 1

This works; I’ve tested it with all of your examples:

^[A-Za-z]+\.([A-Za-z]\.)?[A-Za-z]+$

Explanation:

^ – anchor to match the start of your string
[A-Za-z]+\. – match a letter 1 or more times followed by a period
([A-Za-z]\.)? – optionally match a single letter followed by a period
[A-Za-z]+ – match a letter 1 or more times
$ – anchor to match the end of your string

Hope this helps! For quick reference on regular expressions, see here.