regex - Replace chars if not match

Question

I'm looking for a regular expression that removes illegal characters. But I don't know what the characters will be.

For example:

In a process, I want my string to match ([a-zA-Z0-9/-]*). So I would like to replace all characters that don't match the regexp above.

Answer 1

That would be:

[^a-zA-Z0-9/-]+

[^ ] at the start of a character class negates it - it matches characters not in the class.

See also: Character Classes