COBOL Tables

3/24/2018 COBOL Tables
COBOL TABLES
COBOL TABLES
1. Sequence of consecutive storage locations having a common name.

2. Each location is called an element
3. Each element is referred to by table name and subscript enclosed in parenthesis
4. Subscripts can be constants or variables
USE of TABLES
Must define in working storage

The OCCURS clause is used to define a table
General Format
OCCURS integer TIMES
Where integer = # of elements in Table

Cannot be used with a 01 Level item!
Occurs with elementary items

01 Business-Table.
05 Name OCCURS 50 TIMES PIC X(20).
05 Class OCCURS 50 TIMES PIC X.
05 Hours OCCURS 50 TIMES PIC 9(3).
Table Contains 150 elements

Table Contains 1200 Characters
For this Table, Subscripts may only be used with the
elementary items, thus:
Name(10) is Valid
Class(5) is Valid
Hours(15) is Valid
Business-Table(2) is not Valid!
Occurs with Group Items

01 Business-Table.
05 Student-Data OCCURS 50 TIMES.
10 Name PIC X(20).
10 Class PIC X.
10 Hours PIC 9(3).
Table Contains 150 elements

Table Contains 1200 Characters
For this Table, Subscripts may be used with the
group items and the elementary items, thus:
Student-Data(30) is valid
http://www-personal.k-state.edu/~mchaney/mn670/tables.htm 1/5
Name(10) is Valid
Class(5) is Valid
Hours(15) is Valid
Business-Table(2) is not Valid!
Perform Varying
Used to step through a table to initialize values.

General Format:
PERFORM paragraph VARYING dataname

FROM initial-value BY increment-value
UNTIL condition.
Initial value and increment-value may be either numeric

datanames or numeric constants.
Example
PERFORM PARA-1 VARYING INDX FROM 1 BY 1
UNTIL INDX > 10.
STEPS:
1. INDX is initialized to 1.
2. If condition (INDX > 10) is NOT met, PARA-1 is executed.
3. After PARA-1 is executed, 1 is added to INDX.
4. Return to step 2 and check the condition.
Loading Tables
Execution Time Tables - data loaded when program is run.

Compile Time Tables - data loaded when program is compiled.
Execution Time Tables
Used when data is expected to change often.
1. Define Table in Working-Storage:
01 Business-Table.
05 Student-Data OCCURS 50 TIMES.
10 Name PIC X(20).
10 Class PIC X.
10 Hours PIC 9(3).
01 Num-In PIC 99 VALUE ZERO.
02 ERROR-FLAG PIC X(3) VALUE “NO”.
2. Initialize Table in Procedure Division:
PERFORM Init-Table VARYING Num-In

FROM 1 BY 1 UNTIL Num-In > 50.
.
.
.
Init-Table.
MOVE ZEROS TO Hours(Num-In).
MOVE SPACES TO Name(Num-In)
Class(Num-In).
3. Load data into the table:
MOVE ZERO TO Num-In.

READ Student-File INTO Student-Detail
AT END MOVE “YES” to EOF-FLAG.
PERFORM 100-Load-Table Until EOF-FLAG = “YES”
OR Error-Flag=“YES”.
100-Load-Table.
ADD 1 to Num-In.
IF Num-In > 50 MOVE “YES” TO Error-Flag
ELSE MOVE Name-In to Name(Num-In)
MOVE Class-In to Class(Num-In)
MOVE Hours-In to Hours(Num-In)
READ Student-File INTO Student-Detail
AT END MOVE “YES” to EOF-FLAG.
Compile Time Tables
Used for More Permanent Storage

Days of Week, Month Names, et cetera
In working Storage, define data and table structure.
Values are stored during compilation of program
Uses Redefines clause
REDEFINES
General Format:
Level-Number dataname-1 REDEFINES dataname-2
The level-number on the REDEFINES entry must be the same as the level-number on dataname-2, which is being
redefined.
Define & Load Table in Working-Storage

01 Class-Names.
05 Filler Pic X(9) Value “Freshman”.
05 Filler Pic X(9) Value “Sophomore”.
05 Filler Pic X(9) Value “Junior”.
05 Filler Pic X(9) Value “Senior”.
01 Class-Table REDEFINES Class-Names.

05 Class OCCURS 4 TIMES PIC X(9).
Class-Names and Class-Table are 2 different names

for the same 36 (9 * 4) characters in storage.
FreshmanbSophomoreJuniorbbbSeniorbbb
CLASS(3) = Junior
Redefines Rules
1. Level-Numbers on the REDEFINES entry must be the same as the level-number on the
dataname that is being redefined.
2. A dataname with a lower level-number may NOT occur between the REDEFINES entry and the
dataname being redefined. However, datanames with higher level-numbers are acceptable here.
3. The length of the item being REDEFINED must be exactly the same length as the item it is
redefining.
Indexed by Clause
General Format:
OCCURS integer TIMES INDEXED BY index-name
Example:
01 Class-Names.
05 Filler Pic X(9) Value “Freshman”.
05 Filler Pic X(9) Value “Sophomore”.
05 Filler Pic X(9) Value “Junior”.
05 Filler Pic X(9) Value “Senior”.
01 Class-Table REDEFINES Class-Names.

05 Class OCCURS 4 TIMES
INDEXED BY CLASS-INDEX PIC X(9).
Table Value Occurrence (subscript) Displacement (Index)

Freshman 1 0
Sophomore 2 9
Junior 3 18
Senior 4 27
SUBSCRIPTS vs. INDEXES
When an index-name is specified, the compiler automatically provides for the index. It is not
necessary to define a separate data item in Working-Storage as is done for a variable subscript.
Indexes are displacement values with subscript represent occurrence numbers
Since Index values are displacement values, an index cannot be initialized with a MOVE
statement like a subscript can. Similiarly, we cannot ADD to or SUBTRACT from an index.
Instead, the SET verb must be used.
SET VERB
Used to initialize or change the value of a Table index
To Initialize a table index:
SET index-name TO integer (or numeric variable).
Examples (in procedure division)
SET Class-Index to 1.
SET Class-Index to Class-In.
To INCREMENT OR DECREMENT
SET index-name UP BY (or DOWN BY)

Integer (or numeric variable).
Examples (In Procedure Division)
SET Class-Index UP BY 1.
SET Class-Index Down By 2.

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3/24/2018 COBOL Tables

1. Sequence of consecutive storage locations having a common name.

Must define in working storage

OCCURS integer TIMES

Where integer = # of elements in Table

Occurs with elementary items

Table Contains 150 elements

Occurs with Group Items

Table Contains 150 elements

Used to step through a table to initialize values.

PERFORM paragraph VARYING dataname

Initial value and increment-value may be either numeric

Execution Time Tables - data loaded when program is run.

Execution Time Tables

Used when data is expected to change often.

1. Define Table in Working-Storage:

2. Initialize Table in Procedure Division:

PERFORM Init-Table VARYING Num-In

3. Load data into the table:

MOVE ZERO TO Num-In.

Compile Time Tables

Used for More Permanent Storage

Level-Number dataname-1 REDEFINES dataname-2

Define & Load Table in Working-Storage

01 Class-Table REDEFINES Class-Names.

Class-Names and Class-Table are 2 different names

OCCURS integer TIMES INDEXED BY index-name

01 Class-Table REDEFINES Class-Names.

Table Value Occurrence (subscript) Displacement (Index)

SUBSCRIPTS vs. INDEXES

Used to initialize or change the value of a Table index

To Initialize a table index:

SET index-name TO integer (or numeric variable).

Examples (in procedure division)

SET index-name UP BY (or DOWN BY)

Examples (In Procedure Division)

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