Converts character data in Y to upper or lower-case. This function is considerably faster than any comparable function coded in APL, especially on nested arrays.
Y may be any array of arbitrary depth so long as all the elements are characters.
The optional left-argument X is 0 (convert to lower-case) or 1 (convert to upper-case). If omitted, the default is 0.
The result R has the same structure as Y but each character element is case folded to upper or lower case.
Characters are converted per the default case mappings specified by The Unicode Consortium, described at:
ftp://ftp.unicode.org/Public/3.0-Update/UnicodeData-3.0.0.html
and using the table at:
http://unicode.org/Public/UNIDATA/UnicodeData.txt
If conversion is being used to do case-insensitive character comparisons then converting everything to lower case is generally preferable to converting everything to upper. This is because converting to lower case can be faster.
This I-beam is supported in Classic Edition using the same code as the Unicode Edition. This means that any case-folding defined in the input translate tables is ignored, and that TRANSLATION ERRORs will be generated if the folded characters do not appear in ⎕AV.
(819⌶) 'How many Roads must a man walk down'
how many roads must a man walk down
1 (819⌶) 'How many Roads must a man walk down'
HOW MANY ROADS MUST A MAN WALK DOWN
data←1000⍴⊂'Hello there.'
lc_data←819⌶ data
4↑lc_data
hello there. hello there. hello there. hello there.