Not x.islower() Versus x.isupper Output Results

[Steven D'Aprano]

On Sat, 30 Apr 2016 11:14 am, Christopher Reimer wrote:

> Shouldn't the results between 'not x.islower()' and 'x.isupper()' be
> identical?

Of course not.

py> "2 #".islower(), "2 #".isupper()
(False, False)

py> not "2 #".islower(), "2 #".isupper()
(True, False)

"Is Lower" versus "Is Upper" is not a dichotomy. There are:

- lowercase characters, like "abc"
- uppercase characters, like "ABC"
- characters which are neither lowercase nor uppercase, like "2 #"

In unicode, there are also:

- titlecase characters, like "DžLjῼ"

If those characters don't show up for you, they are:

U+01C5  LATIN CAPITAL LETTER D WITH SMALL LETTER Z WITH CARON
U+01C8  LATIN CAPITAL LETTER L WITH SMALL LETTER J
U+1FFC  GREEK CAPITAL LETTER OMEGA WITH PROSGEGRAMMENI


So not islower() is very different from isupper.




-- 
Steven