Regex must contain specific letters in any order

Question

I have been attempting to validate a string in VB.net that must contain these three letters in no particular order and do not need to be next to One another. ABC

I can do this easily using LINQ

MessageBox.Show(("ABC").All(Function(n) ("AAAABBBBBCCCC").Contains(n)).ToString)

However, after searching Google and SO for over a week, I am completely stumped. My closest pattern is ".*[A|B|C]+.*[A|B|C]+.*[A|B|C]+.*" how ever AAA would also return true. I know i can do this using other methods just after trying for a week i really want to know if its possible using One regular expression.

Answer 1

Your original pattern won't work because it will match any number of characters, followed by one or more A, B, C, or | character, followed by any number of characters, followed by one or more A, B, C, or | character, followed by any number of characters, followed by one or more A, B, C, or | character, followed by any number of characters.

I'd probably go with the code you've already written, but if you really want to use a regular expression, you can use a series of lookahead assertions, like this:

(?=.*A)(?=.*B)(?=.*C)

This will match any string that contains A, B, and C in any order.