There are occasions when you may wish to set a variable to
an infinitely high or infinitely low number. For example, suppose you were
merging two files on surnames as the primary key:
A D V E R T I S E M E N T
*in data division FILE SECTION
FD FILE-1.
01 RECORD-1.
03 IN-NAME-1 PIC X(20).
03 FILLER PIC X(50).
FD MERGE-FILE.
01 RECORD-OUT PIC X(70).
:
:
PERFORM WITH TEST AFTER EOF-FLAG-1 AND EOF-FLAG-2
*loop until each file has been read to completion
*read each file
READ FILE-1
AT END SET EOF-FLAG-1 TO TRUE MOVE HIGH-VALUES TO IN-NAME-1
END-READ
READ FILE-2
AT END SET EOF-FLAG-2 TO TRUE MOVE HIGH-VALUES TO IN-NAME-2
END-READ
*sort the records (assuming no 2 names are the same)
*on ascending surname
IF IN-NAME-1 IS < IN-NAME-2 THEN
WRITE RECORD-OUT FROM RECORD-1
ELSE
WRITE RECORD-OUT FROM RECORD-2
END-IF
END-PERFORM
In this example, when IN-NAME-1 is less than IN-NAME-2
(based on their ASCII values e.g. A < B etc..) then the FILE-1 record (RECORD-1)
is written to the merge file (RECORD-OUT). One of FILE-1 and FILE-2 will come to
an end before the other so the completed file has its IN-NAME-_ value set to
constant that will ALWAYS be greater than the IN-NAME-_ value still being read,
ensuring all remain files are written to the merge file. This is done with the
lines: MOVE HIGH-VALUES TO IN-NAME-1 and MOVE HIGH-VALUES TO IN-NAME-2
It is important to note that HIGH-VALUES and LOW-VALUES
are ALPHANUMERIC in type, so you can't set numerically defined variables
to this type (you would have to
implicitly redefine the
variable first). This is an annoying quirk of COBOL.
