Allow alphanumeric chars and max one space

Question

I need a regex to make the validation of an username field. I need to accept just alphanumeric chars and max one space.

What I tried is:

^[a-z0-9]+[ ][a-z0-9]+$

It's working but it doesn't seems the right solution for this problem. Can someone guide me on how to optimize this regex? Thanks.

Assuming that space shouldn't come at the end or beginning it should be `^(?:[a-z0-9]+ )?[a-z0-9]+$` — revo, May 25 '19 at 12:53
Seems that is working better, thanks. However yes, since it's an username validation field, the string is going to be trimmed automatically at the beginning and at the end. — Keaire, May 25 '19 at 13:02

score 0 · Answer 1 · answered May 25 '19 at 14:15

0

The following regular expression will do it: ^[a-zA-Z0-9]+ ?[a-zA-Z0-9]+$

You missed only the ? character after the space, what matches between zero and one times.

answered May 25 '19 at 14:15

Norbert Incze

A username usually must be longer than 6 characters. – Norbert Incze May 25 '19 at 14:36
Yes, we just can guess about it and my first comment was just an FYI. – revo May 25 '19 at 14:45

1 Answers1