Error handling after increasing the array index

After increasing the array index, an error handling must be included, because if the input is extended later again, we can look for the error again. A handled error is easier to find and fix than a buffer overwrite error.
Table index should start from 0, because it indicates better that the table is empty.

Signed-off-by: Janos Varga <[email protected]>

Author: vargajb

COBOL Programming Course #3 - Advanced Topics/Challenges/Debugging/cbl/CBL0106C.cbl

@@ -44,9 +44,10 @@
       *
        WORKING-STORAGE SECTION.
        01  Filler.
-           05 LASTREC          PIC X VALUE SPACE.
+           05 LASTREC          PIC X          VALUE SPACE.
            05 DISP-SUB1        PIC 9999.
            05 SUB1             PIC 99.
+           05 OVERLIMIT-MAX    PIC S9(4) COMP VALUE 20.
 
          01 OVERLIMIT.
            03 FILLER OCCURS 20 TIMES.
@@ -136,7 +137,7 @@
            WRITE PRINT-REC FROM HEADER-3.
            WRITE PRINT-REC FROM HEADER-4.
            MOVE SPACES TO PRINT-REC.
-           MOVE 1 TO SUB1.
+           MOVE 0 TO SUB1.
       *
        READ-NEXT-RECORD.
            PERFORM READ-RECORD
@@ -162,11 +163,19 @@
       *
        IS-OVERLIMIT.
            IF ACCT-LIMIT < ACCT-BALANCE THEN
+               ADD 1 TO SUB1
+      * Check if there is enough space in the array, in case the input 
+      * file changes again. A handled error is easier to find and fix 
+      * than a buffer overwrite error.
+               IF SUB1 > OVERLIMIT-MAX THEN
+                   DISPLAY 'OVERFOLW TABLE OVERLIMIT'
+                   MOVE 1000 TO RETURN-CODE
+                   STOP RUN
+               END-IF
                MOVE ACCT-LIMIT TO OL-ACCT-LIMIT(SUB1)
                MOVE ACCT-BALANCE TO OL-ACCT-BALANCE(SUB1)
                MOVE LAST-NAME TO OL-LASTNAME(SUB1)
                MOVE FIRST-NAME TO OL-FIRSTNAME(SUB1)
-               ADD 1 TO SUB1
             END-IF.
       *
        IS-STATE-VIRGINIA.
@@ -175,7 +184,7 @@
            END-IF.
       *
        WRITE-OVERLIMIT.
-           IF SUB1 = 1 THEN
+           IF SUB1 = 0 THEN
                MOVE OVERLIMIT-STATUS TO PRINT-REC
                WRITE PRINT-REC
            ELSE