~ Bubble sort: demonstrates array indexing
"!Enter numbers to be sorted (0 terminates): "

0 1 - Z:                            ~ Set number counter
(? X: X. 0> ^                       ~ Read number and check > 0
   Z. 1 + Z: X. A Z. + : )          ~ Count number and store it
Z. X:                               ~ Set bound for first scan
( X. Y: 0 X: 0 W:                   ~ Prepare for scan
   ( W. Y. < ^                      ~ Scan until bound reached
      A W. + . A W. 1 + + . >       ~ Compare two items of list
         [ A W. + . A W. 1 + + .    ~ Swap them
           A W. + : A W. 1 + + :
           W. X: ]                  ~ Update bound
      W. 1 + W: )                   ~ Move to next pair
   X. 0 > ^)                        ~ Continue if a swap occurred
"!Sorted array: "
0 X:                                ~ Set subscript
( A X. + . ! " "                    ~ Display one item
   X. Z. < ^                        ~ Check if done
   X. 1 + X: )                      ~ Move to next item
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