Regex for given parameters

Question

I recently had test with regex, but I am not skilled in it. I try to write something for pattern:

• String must contains 6-16 chars
• String should be start only from char
• String could contain any char, but "-" only once
• String must not end with "-"

I wrote somethin like this "(^[a-zA-Z]).(/w{6,16}).*(?<!-)$", ofcourse it is not correct and not full.

I am very interesting in correct answear with explanaition, you could downvote my question if you think, it shoud be.

Answer 1

You may use

^[a-zA-Z](?=.{5,15}$)[^-]*(?:-[^-]+)?$

See the regex demo

Details

• ^ - start of string
• [a-zA-Z] - an ASCII letter
• (?=.{5,15}$) - a positive lookahead requiring 5 to 15 chars up to the string end from the current position
• [^-]* - (a negated character class) 0+ chars other than -
• (?:-[^-]+)? - an optional non-capturing group that matches 1 or 0 repetitions of
  • - - a hyphen
  • [^-]+ - 1+ chars other than -
• $ - end of string