help with regular expressions

[Anon]

Is it possible to set up a regular expression that conforms to the following tests.

Start with a letter or number.
End with a letter or number.
Must only be a total of 20 character long.
Must be a minimum of 3 character long.
The middle characters must only be a letter, number, underscore, hyphen,space or full stop.

I was thinking something like,

^{[a-zA-Z0-9][a-zA-Z0-9_-} .]{1,18}$[a-zA-Z0-9]

but it doesn't work.

Thanx in advance,

Ben Graves.

[[deleted]]

move the $ to the end of the pattern. (it means 'match end of string', so there can be nothing after it anyway)

[Anon]

And I'd also move that last hyphen in the middle character class to the start of the class - it means "match any character between underscore and space".