Chapter 16. MULTIPLE-LEVEL ARRAYS AND TABLES
Upon completion of this chapter, you should be able to
Establish a series of items using a double-level OCCURS clause.
Demonstrate how to establish a series of items within a multiple-level array.
Demonstrate how to look up data stored in a multiple-level array.
Access and manipulate data defined with a triple-level (or more) OCCURS clause.
DOUBLE-LEVEL OCCURS CLAUSE
When describing an area of storage, as many as seven levels of OCCURS are permitted.
Like a single-level OCCURS, multiple levels of OCCURS may be used for (1) accumulating totals in an array, or (2) storing a table for "look-up" purposes. We will look first at multiple-level arrays and then at multiple-level tables.
DEFINING A DOUBLE-LEVEL, OR TWO-DIMENSIONAL, ARRAY
Suppose we wish to establish in storage an array of hourly temperature readings for Los Angeles or any other city during a given week. Once the array is established, it is used to perform various calculations. The array consists of 7 × 24 temperature readings; that is, there are 24 hourly temperature readings for each of 7 days. The array is represented as
To define this array in WORKING-STORAGE with a single-level OCCURS would require the following coding.
The ellipses, or dots (. . .), indicate that 24 elementary ...