Rules for occurs clause, COBOL Programming


The rules apply for the OCCURS clause and the subscripts are as shown below.

(1) The integer in the OCCURS clause should be a positive integer.

(2) The OCCURS clause can be identified for an elementary item or for a group item. The clause causes adjoining fields to be set up internally. Each field is alike to the elementary or group item for which the OCCURS clause has been identified. The number of fields which are set up is equivalent to the integer in the OCCURS clause. The OCCURS clause cannot be identified for an item whose level numbers are 01, 66, 77 or 88.

(3) Whenever a data name is defined with occur clause which the data name as well as any of its subordinate items cannot be referred to in the PROCEDURE DIVISION without a subscript. It may be a positive integer constant, a numeric integral data or an arithmetic expression. For illustration, an element of the above INCOME-TAX-RATE table, can be referred to the PROCEDURE DIVISION as

      TAX-RATE (I)    or as (3*J)

In the initial situation, a data name I has been used as the subscript. If the current value of I is, 5, then the TAX-RATE (I) will refer to the fifth element of the table. In the second situation, an arithmetic expression has been used as the subscript. The value of the expression is used to specify the particular element of the table. Therefore, if the present value of J is 1, TAX-RATE (3*J) will refer to the third element of the table.

(4) The maximum value which a subscript can take is the one specified in the OCCURS clause. For any table, the minimum value of a subscript is implicitly supposed to be 1. By the range of a subscript we mean the range of values from 1 to the maximum possible value of the subscript. In the above illustration, the range of the subscript is 1-10. If during the execution of a program, the value of subscript is found to be outside its range, then an execution error occurs and the program is finished by the system.

(5) The subscripts must be enclosed in a set of parentheses. In common, blank space may not follow the left parenthesis while there should be a space preceding the left parenthesis and following the right one.

(6) When a data name with the OCCURS clause needs any qualification by its higher level, the subscripts to be written after the final qualified name. For illustration, if TAX-RATE must be qualified, it should appear as TAX-RATE OF INCOME-TAX-RATE (I) and not as the TAX-RATE (I) OF INCOME-TAX-RATE.

(7) Whenever an entry is defined with the OCCURS clause, the VALUE clause cannot be identified for that specific item or any item subordinate to it.

(8) The REDEFINES clause cannot appear in similar data description entry that contains an OCCURS clause. Though, the REDEFINES clause can appear for a group item whose subordinate items are defined with occur clause.

(9) The OCCURS clause can appear in the data description entry in any order. 

Posted Date: 10/18/2012 1:33:31 AM | Location : United States

Related Discussions:- Rules for occurs clause, Assignment Help, Ask Question on Rules for occurs clause, Get Answer, Expert's Help, Rules for occurs clause Discussions

Write discussion on Rules for occurs clause
Your posts are moderated
Related Questions
File volatility: File volatility associates to the number of times the updating of records are needed during some time period. File interrogation: Some files hold re

Structure of a COBOL Program: Every COBOL program should have the 4 divisions in the order in which they are specified below: 1. Identification division 2. Environment D

DISPLAY STATEMENT:   The function of the DISPLAY statement is just opposite to that of the ACCEPT statement. It is used to display the low-volume results on the operator's co

Example of Redefines clause: This illustration describes a sales record that may either contain the total amount of sale or the quantity (QTY) and UNIT-PRICE. The aim of such

Rules of read statements: The next record is identified according to the rules as shown below: (i) Whenever the READ NEXT statement is the initial statement to be executed

Direct Organization: Besides the relative or indexed organization, also a direct access file can be designed to have what is termed as direct organization.  In this organizati

Block Size: The normal practice is to group a number of consecutive records to form that is termed as a block or a physical record. The number of records in a block is frequen

Illustration of nested if statement: Consider the nested sentence which is as shown below: The IF-ELSE pairs in this sentence can be detected by applying the rule whic

Example of read statement: Illustration: READ OLD-MASTER AT END MOVE ZERO TO END-OF-RECORDS. As a result of this statement, generally the next record from the OLD-MAST

Example of Level numbers - cobol programming: To explain the hierarchical structure introduced above, the concept of the level number is employed in COBOL. The most broad