Question

I want a regular expression for a string
This string can contain * and ? in it. But should have at least 3 alphanumeric character in it.
So,

*abc* is valid
*ab*c is valid
*aaa? is valid
*aa  is not valid
**aaa is not valid as it is not a valid regular expression

Answer 1

This should do it:

^[*?]?([0-9a-z][*?]?){3,}$

Explanation:

• ^ matches the beginning of the string
• [*?]? matches an optional * or ?
• (...){3,} the group must appear at least 3 times
• [0-9a-z][*?]? matches an alphanumeric character followed by an optional * or ?
• $ matches the end of the string

Consecutive * and ? are not matched.

Update: Forgot to mention it, but it was on my mind: Use i modifier to make the match case-insensitive (/.../i).