COBOL - Data Types

Data Division is used to define the variables used in a program. To describe data in COBOL, one must understand the following terms −

Data Name

Level Number

Picture Clause

Value Clause

01            TOTAL-STUDENTS            PIC9(5)            VALUE  125 .
|                    |                    |                    |
|                    |                    |                    |
|                    |                    |                    | 
Level Number     Data Name           Picture Clause       Value Clause

Data Name

Data names must be defined in the Data Division before using them in the Procedure Division. They must have a user-defined name; reserved words cannot be used. Data names give reference to the memory locations where actual data is stored. They can be elementary or group type.

Example

The following example shows vapd and invapd data names −

Vapd:
   WS-NAME
   TOTAL-STUDENTS
   A100
   100B

Invapd:
   MOVE            (Reserved Words)
   COMPUTE         (Reserved Words)
   100             (No Alphabet)
   100+B           (+ is not allowed) 

Level Number

Level number is used to specify the level of data in a record. They are used to differentiate between elementary items and group items. Elementary items can be grouped together to create group items.

Elementary items cannot be spanided further. Level number, Data name, Picture clause, and Value clause (optional) are used to describe an elementary item.

Group items consist of one or more elementary items. Level number, Data name, and Value clause (optional) are used to describe a group item. Group level number is always 01.

Example

The following example shows Group and Elementary items −

DATA DIVISION.
WORKING-STORAGE SECTION.
01 WS-NAME    PIC X(25).                               ---> ELEMENTARY ITEM 
01 WS-CLASS   PIC 9(2)  VALUE   10 .                   ---> ELEMENTARY ITEM

01 WS-ADDRESS.                                         ---> GROUP ITEM   
   05 WS-HOUSE-NUMBER    PIC 9(3).                     ---> ELEMENTARY ITEM
   05 WS-STREET          PIC X(15).                    ---> ELEMENTARY ITEM
   05 WS-CITY            PIC X(15).                    ---> ELEMENTARY ITEM
   05 WS-COUNTRY         PIC X(15)  VALUE  INDIA .     ---> ELEMENTARY ITEM

Picture Clause

Picture clause is used to define the following items −

Data type can be numeric, alphabetic, or alphanumeric. Numeric type consists of only digits 0 to 9. Alphabetic type consists of letters A to Z and spaces. Alphanumeric type consists of digits, letters, and special characters.

Sign can be used with numeric data. It can be either + or –.

Decimal point position can be used with numeric data. Assumed position is the position of decimal point and not included in the data.

Length defines the number of bytes used by the data item.

Symbols used in a Picture clause −

Example

The following example shows the use of PIC clause −

IDENTIFICATION DIVISION.
PROGRAM-ID. HELLO.

DATA DIVISION.
   WORKING-STORAGE SECTION.
   01 WS-NUM1 PIC S9(3)V9(2).
   01 WS-NUM2 PIC PPP999.
   01 WS-NUM3 PIC S9(3)V9(2) VALUE -123.45.
   01 WS-NAME PIC A(6) VALUE  ABCDEF .
   01 WS-ID PIC X(5) VALUE  A121$ .

PROCEDURE DIVISION.
   DISPLAY "WS-NUM1 : "WS-NUM1.
   DISPLAY "WS-NUM2 : "WS-NUM2.
   DISPLAY "WS-NUM3 : "WS-NUM3.
   DISPLAY "WS-NAME : "WS-NAME.
   DISPLAY "WS-ID : "WS-ID.
STOP RUN.

//SAMPLE JOB(TESTJCL,XXXXXX),CLASS = A,MSGCLASS = C
//STEP1 EXEC PGM = HELLO

WS-NUM1 : +000.00
WS-NUM2 : .000000
WS-NUM3 : -123.45
WS-NAME : ABCDEF
WS-ID : A121$

IDENTIFICATION DIVISION.
PROGRAM-ID. HELLO.

DATA DIVISION.
   WORKING-STORAGE SECTION.
   01 WS-NUM1 PIC 99V9 VALUE IS 3.5.
   01 WS-NAME PIC A(6) VALUE  ABCD .
   01 WS-ID PIC 99 VALUE ZERO.

PROCEDURE DIVISION.
   DISPLAY "WS-NUM1 : "WS-NUM1.
   DISPLAY "WS-NAME : "WS-NAME.
   DISPLAY "WS-ID   : "WS-ID.
STOP RUN.

//SAMPLE JOB(TESTJCL,XXXXXX),CLASS = A,MSGCLASS = C
//STEP1 EXEC PGM = HELLO

WS-NUM1 : 03.5
WS-NAME : ABCD
WS-ID   : 00