Regex that can only contain alphanumeric characters and underscores, but the first character must be alphabetical (single character failure)

Question

I have the following regex pattern:

^[A-Za-z][A-Za-z0-9_-]+$`

It is used to match; alphanumeric characters, underscores and dashes, with the first character being alphabetical.

This works as expected, but I also need it to be able to match single characters. A conditions of a fails.

How can I modify the pattern to make a single alphabetical character pass?

*\* (zero or more times) + (one or more times)* – Wiktor Stribiżew Feb 10 '16 at 09:36 — Wiktor Stribiżew, Feb 10 '16 at 09:36

score 4 · Answer 1 · answered Feb 10 '16 at 09:34

4

^[A-Za-z][A-Za-z0-9_-]*$

This shoudl do it for you

answered Feb 10 '16 at 09:34

vks

Could you explain the significance of using `*` instead of `+`? – S-K' Feb 10 '16 at 09:36
@S-K' `*` mean `0 or more` `+` means `1 or more` – vks Feb 10 '16 at 09:36

score 4 · Accepted Answer · answered Feb 10 '16 at 09:35

4

The + means "one or more". Replace it with * for "zero or more".

answered Feb 10 '16 at 09:35

2 Answers2