INDEXED BY and OCCURS DEPENDING ON

INDEXED BY

INDEXED BY adds an index register to the table. The index holds the entry number in a form the CPU can use directly, which is faster than a subscript on large tables:

01 WS-STAFF. 05 WS-NAME OCCURS 100 TIMES INDEXED BY WS-STAFF-IX PIC X(30).

SET and indexes

Indexes move with SET, not MOVE. SET UP and SET DOWN step by one, and you can assign an index from another index or a literal:

SET WS-STAFF-IX TO 1. SET WS-STAFF-IX UP BY 1. SET WS-STAFF-IX DOWN BY 2.

OCCURS DEPENDING ON

OCCURS DEPENDING ON makes the used length depend on a variable. The table reserves its maximum size, but loops and FILE records only see the used entries:

01 WS-ROW-COUNT PIC 9(2) VALUE 0. 01 WS-ROWS. 05 WS-ROW OCCURS 1 TO 50 TIMES DEPENDING ON WS-ROW-COUNT PIC X(20).

Next: Paragraphs and sections

Article author: Arthur Isaev