Oh I was already operating under the assumption that you split the segments. The purpose of this was to give an idea of how to handle hyphens. Of course you should replace the dots with the appropriate character classes :)
It also accepts two characters, so that's not ideal. Maybe change the middle * to a +
Oh!
Then we're only missing the alternating hyphen and it's done.
^[a-z](-[a-z0-9])?([a-z0-9]-[a-z0-9]|[a-z0-9])*([a-z0-9]-)?[a-z0-9](?:\.[a-z](-[a-z0-9])?([a-z0-9]-[a-z0-9]|[a-z0-9])*([a-z0-9]-)?[a-z0-9])*$More tests:
How about
Alternating hyphens wouldn't work either
Further testing:
How about
Over eager in matching that last character. I should actually put your test cases into a tester before throwing this out there haha... I'll do that next time I swear.
I did it! You weren't far! You just had to delete the first character acceptance in your last .-., since the previous section already ended in letter/number.
^[a-z](-[a-z0-9](-[a-z0-9])*)?(-[a-z0-9]|[a-z0-9])*(?:\.[a-z](-[a-z0-9](-[a-z0-9])*)?(-[a-z0-9]|[a-z0-9])*)*$Now wondering if it's possible to add a maximum number of characters in this regex.
Working the same way as before.
^[a-z](-[a-z0-9](-[a-z0-9])*)?([a-z0-9]-[a-z0-9]|[a-z0-9])*(?:[a-z](-[a-z0-9](-[a-z0-9])*)?([a-z0-9]-[a-z0-9]|[a-z0-9])*)$My bad, it actually works better
^[a-z](-[a-z0-9](-[a-z0-9])*)?([a-z0-9]-[a-z0-9]|[a-z0-9])*(?:[a-z](-[a-z0-9](-[a-z0-9])*)?([a-z0-9]-[a-z0-9]|[a-z0-9])*)*$It's actually working pretty well. I had just missed a period.
but it's still missing a test case.
Further testing:
And more tests:
& more