Category: cobol

COBOL – Data Types ”; Previous Next 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 valid and invalid data names − Valid: WS-NAME TOTAL-STUDENTS A100 100B Invalid: 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. Sr.No. Level Number & Description 1 01 Record description entry 2 02 to 49 Group and Elementary items 3 66 Rename Clause items 4 77 Items which cannot be sub-divided 5 88 Condition name entry Elementary items cannot be divided 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 − Sr.No. Symbol & Description 1 9 Numeric 2 A Alphabetic 3 X Alphanumeric 4 V Implicit Decimal 5 S Sign 6 P Assumed Decimal Example The following example shows the use of PIC clause − Live Demo 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$”. PROCEDURE DIVISION. DISPLAY “WS-NUM1 : “WS-NUM1. DISPLAY “WS-NUM2 : “WS-NUM2. DISPLAY “WS-NUM3 : “WS-NUM3. DISPLAY “WS-NAME : “WS-NAME. DISPLAY “WS-ID : “WS-ID. STOP RUN. JCL to execute the above COBOL program − //SAMPLE JOB(TESTJCL,XXXXXX),CLASS = A,MSGCLASS = C //STEP1 EXEC PGM = HELLO When you compile and execute the above program, it produces the following result − WS-NUM1 : +000.00 WS-NUM2 : .000000 WS-NUM3 : -123.45 WS-NAME : ABCDEF WS-ID : A121$ Value Clause Value clause is an optional clause which is used to initialize the data items. The values can be numeric literal, alphanumeric literal, or figurative constant. It can be used with both group and elementary items. Example The following example shows the use of VALUE clause − Live Demo 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. JCL to execute the above COBOL program − //SAMPLE JOB(TESTJCL,XXXXXX),CLASS = A,MSGCLASS = C //STEP1 EXEC PGM = HELLO When you compile and execute the above program, it produces the following result − WS-NUM1 : 03.5 WS-NAME : ABCD WS-ID : 00 Print Page Previous Next Advertisements ”;

COBOL – File Organization ”; Previous Next File organization indicates how the records are organized in a file. There are different types of organizations for files so as to increase their efficiency of accessing the records. Following are the types of file organization schemes − Sequential file organization Indexed sequential file organization Relative file organization The syntaxes in this module, mentioned along with their respective terms, only refer to their usage in the program. The complete programs using these syntaxes would be discussed in the chapter ”File handling Verbs”. Sequential File Organization A sequential file consists of records that are stored and accessed in sequential order. Following are the key attributes of sequential file organization − Records can be read in sequential order. For reading the 10th record, all the previous 9 records should be read. Records are written in sequential order. A new record cannot be inserted in between. A new record is always inserted at the end of the file. After placing a record into a sequential file, it is not possible to delete, shorten, or lengthen a record. Order of the records, once inserted, can never be changed. Updation of record is possible. A record can be overwritten, if the new record length is same as the old record length. Sequential output files are good option for printing. Syntax Following is the syntax of sequential file organization − INPUT-OUTPUT SECTION. FILE-CONTROL. SELECT file-name ASSIGN TO dd-name-jcl ORGANIZATION IS SEQUENTIAL Indexed Sequential File Organization An indexed sequential file consists of records that can be accessed sequentially. Direct access is also possible. It consists of two parts − Data File contains records in sequential scheme. Index File contains the primary key and its address in the data file. Following are the key attributes of sequential file organization − Records can be read in sequential order just like in sequential file organization. Records can be accessed randomly if the primary key is known. Index file is used to get the address of a record and then the record is fetched from the data file. Sorted index is maintained in this file system which relates the key value to the position of the record in the file. Alternate index can also be created to fetch the records. Syntax Following is the syntax of indexed sequential file organization − INPUT-OUTPUT SECTION. FILE-CONTROL. SELECT file-name ASSIGN TO dd-name-jcl ORGANIZATION IS INDEXED RECORD KEY IS primary-key ALTERNATE RECORD KEY IS rec-key Relative File Organization A relative file consists of records ordered by their relative address. Following are the key attributes of relative file organization − Records can be read in sequential order just like in sequential and indexed file organization. Records can be accessed using relative key. Relative key represents the record’s location relative to the address of the start of the file. Records can be inserted using relative key. Relative address is calculated using relative key. Relative file provides the fastest access to the records. The main disadvantage of this file system is that if some intermediate records are missing, they will also occupy space. Syntax Following is the syntax of relative file organization − INPUT-OUTPUT SECTION. FILE-CONTROL. SELECT file-name ASSIGN TO dd-name-jcl ORGANIZATION IS RELATIVE RELATIVE KEY IS rec-key Print Page Previous Next Advertisements ”;