Regex for username that allows numbers, letters and spaces

Question

I\'m looking for some regex code that I can use to check for a valid username.

I would like for the username to have letters (both upper case and lower case), number

Answer 1

Although I'm sure someone will shortly post a 1 million lines regex to do exactly what you want, I don't think in this case a regex is a good solution.

Why don't you write a good old fashioned parser? It will take about as long as writing the regex that does everything you mentioned, but it's going to be much easier to maintain and read.

In particular, this is the tricky part:

it should also not allow for any of the special characters listed above to be repeated more than once in succession

Alternatively you can always do a hybrid of the two. A regex for the other checks ([a-zA-Z0-9][a-zA-Z0-9 _-\.]*[a-zA-Z0-9]) and a non-regex method for the no-repeat requirement.