You can convert the array elements to lowercase while comparing them. With 
@items=sort { lc($a) cmp lc($b) } (@items);

[download]
your code prints: 
A
a
B
b
C
c

[download]

Update: sort lists this with uc as example.

In reply to Re: sorting text arrays and ignoring case by matze
in thread sorting text arrays and ignoring case by slloyd

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