There is no special for statement for scanning a
“multidimensional” array. There cannot be one, because, in truth,
awk does not have
multidimensional arrays or elements—there is only a
multidimensional way of accessing an array.
However, if your program has an array that is always accessed as
multidimensional, you can get the effect of scanning it by combining
the scanning for statement
(see Scanning All Elements of an Array) with the
built-in split() function
(see String-Manipulation Functions).
It works in the following manner:
for (combined in array) {
split(combined, separate, SUBSEP)
...
}
This sets the variable combined to
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 individual indices then become the elements of
the array separate.
Thus, if a value is previously stored in array[1, "foo"], then
an element with index "1\034foo" exists in array. (Recall
that the default value of SUBSEP is the character with code 034.)
Sooner or later, the for statement finds that index and does an
iteration with the variable combined set to "1\034foo".
Then the split() function is called as follows:
split("1\034foo", separate, "\034")
The result is to set separate[1] to "1" and
separate[2] to "foo". Presto! The original sequence of
separate indices is recovered.