This function returns the number of values that are contained inside the
specified array. Notice that zeros and empty strings at the end of this array
are not counted towards this number. Also, counting will stop when a 0 or empty string is encountered.

For example:

setarray @array[0], 100, 200, 300, 400, 500, 600;
set @arraysize,getarraysize(@array);

This will make @arraysize == 6. But if you try this:

setarray @array[0], 100, 200, 300, 400, 500, 600, 0, 500;
set @arraysize,getarraysize(@array);

@arraysize will still equal 6, even though you've set 8 values.