
Idiomatically determine all the lowercase and uppercase letters   (of the Latin [English] alphabet)   being used currently by a computer programming language.
The method should find the letters regardless of the hardware architecture that is being used (ASCII, EBCDIC, or other).



Task requirements
Display the set of all:

   lowercase letters 
   uppercase letters

that can be used (allowed) by the computer program,


where   letter   is a member of the Latin (English) alphabet:     a ──► z     and     A ──► Z.



You may want to mention what hardware architecture is being used, and if applicable, the operating system.



See also
 Idiomatically determine all the characters that can be used for symbols.


/*REXX program determines what characters are  lowercase and uppercase  (Latin) letters.*/
$L=                                              /*set lowercase alphabet string to null*/
$U=                                              /* "  uppercase     "       "    "   " */
    do #=0  for 2**8                             /*traipse through  all  the characters.*/
                                       _=d2c(#)  /*convert decimal number to character. */
    if datatype(_, 'L')  then $L=$L || _         /*Lowercase?  Then add char to the list*/
    if datatype(_, 'U')  then $U=$U || _         /*Uppercase?    "   "   "    "  "    " */
    end   /*#*/                                  /* [↑]  put all the letters into a list*/
 
say '    lowercase letters: '   $L               /*display all the  lowercase  letters. */
say '    uppercase letters: '   $U               /*   "     "   "   uppercase     "     */
                                                 /*stick a fork in it,  we're all done. */