Scanning Multi-dimensional Arrays
=================================

   There is no special `for' statement for scanning a
"multi-dimensional" array; there cannot be one, because in truth there
are no multi-dimensional arrays or elements; there is only a
multi-dimensional *way of accessing* an array.

   However, if your program has an array that is always accessed as
multi-dimensional, you can get the effect of scanning it by combining
the scanning `for' statement (see Scanning all Elements of an Array: Scanning an Array.) with the `split' built-in function (*note Built-in
Functions for String Manipulation: String Functions.).  It works like
this:

     for (combined in ARRAY) {
       split(combined, separate, SUBSEP)
       ...
     }

This finds each concatenated, combined index in the array, and splits it
into the individual indices by breaking it apart where the value of
`SUBSEP' appears.  The split-out indices become the elements of the
array `separate'.

   Thus, suppose you have previously stored in `ARRAY[1, "foo"]'; then
an element with index `"1\034foo"' exists in ARRAY.  (Recall that the
default value of `SUBSEP' contains the character with code 034.)
Sooner or later the `for' statement will find that index and do an
iteration with `combined' set to `"1\034foo"'.  Then the `split'
function is called as follows:

     split("1\034foo", separate, "\034")

The result of this is to set `separate[1]' to 1 and `separate[2]' to
`"foo"'.  Presto, the original sequence of separate indices has been
recovered.