[^ ] 	Matches a single character that is not contained within the brackets. For example, [^abc] matches any character other than "a", "b", or "c". 

[^a-z] matches any single character that is not a lowercase letter from "a" to "z". As above, literal characters and ranges can be mixed.

^[hc]at matches "hat" and "cat", but only at the beginning of the string or line.