Case Convert R←{X}(819⌶)Y

Note

This i-beam function has been replaced by a system function and is deprecated. See Case Convert.

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.

Examples

      (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.