is the regex [a-Z] valid and if yes then is it the same as [a-zA-Z]

Question

is the regex [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 capital

Edit:

i received some answers specifiying that while [a-Z] is not valid then [A-z] is valid (but wont be the same as [a-zA-Z]) and this is really what i was looking for. since i wanted to know in general if its possible to replace [a-zA-Z] with a more compact version. thanks for all who contributed to the answer.

Answer 1

You could always try it:

 print "ok" if "monkey" =~ /[a-Z]/;

Perl says

Invalid [] range "a-Z" in regex; marked by <-- HERE in m/[a-Z <-- HERE ]/ at a-z.pl line 4.

Answer 2

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.

Answer 3

Um, why not try it and find out. It looks like it should be and it looks like it should match.

Try:

string = "AbCdefG"
string =~ s/[a-Z]+//g

And see if that works. That will tell you straight away. You should end up with the empty string.

Answer 4

No its not valid probably because the acsii values are not consecutive from z to A

Answer 5

No, a (97) is higher than Z (90). [a-Z] isn't a valid character class. However [A-z] wouldn't be equivalent either, but for a different reason. It would cover all the letters but would also include the characters between the uppercase and lowercase letters: [\]^_` .

Answer 6

You don't specify what language, but in general [a-Z] won't be a valid range, as in ASCII the lower-case alpha characters come after the upper-case ones. [A-z] might be a valid range (indicating all upper- and lower-cased alphas as well as the punctuation that appears between Z and a), but it might not be, depending on your particular implementation. The i flag can be added to the regex to make it case-insensitive; check your particular implementation for instructions on how to specify that flag.

Answer 7

If it's valid, it won't do what you expect.

The character code of Z is lower than the character code of a, so if the codes are swapped to mean the range [Z-a], it will be the same as [Z\[\\\]^_`a], i.e. it will include the characters Z and a, and the characters between.

If you use [A-z] to get all upper and lower case characters, that is still not the same as [A-Za-z], it's the same as [A-Z\[\\\]^_`a-z].