Is the regular expression [a-Z] valid and if yes then is it the same as [a-zA-Z]?

Question

Is the regular expression [a-Z] valid and if yes then is it the same as [a-zA-Z]? Please note that in [a-Z] the a is lowercase and the Z is uppercase.

E

Answer 1

I'm not sure about other languages' implementations, but in PHP you can do

"/[a-z]/i"

and it will case insensitive. There is probably something similar for other languages.