Difference between regex [A-z] and [a-zA-Z]

Question

I am using a regex to program an input validator for a text box where I only want alphabetical characters. I was wondering if [A-z] and [a-zA-Z] we

Answer 1

[A-z] will match ASCII characters in the range from A to z, while [a-zA-Z] will match ASCII characters in the range from A to Z and in the range from a to z. At first glance, this might seem equivalent -- however, if you look at this table of ASCII characters, you'll see that A-z includes several other characters. Specifically, they are [, \, ], ^, _, and ` (which you clearly don't want).