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PowerPoint Presentation:Richard H. Baum, Ph.D.DeVry Institute of TechnologyEdited By: Charmaine Salvador-Ponay(UST) for lecture purposes

9th Edition

Structured COBOLProgramming

Nancy SternHofstra University

Robert A. Stern

Nassau CommunityCollege

“Copyright @ 2000 John Wiley & Sons, In. All rightsreserved. Reproduction or translation of this work

beyond that permitted in Section 117 of the 1976United States Copyright Act without the expresspermission of the copyright owner is unlawful.Request for further information should be addressedto the permissions Department , John Wily & Sons,Inc. The purchaser may make back-up copies forhis/her own use only and not for distribution orresale. The Publisher assumes no responsibility forerrors, omissions, or damages, caused by the use ofthese programs or from the use of the informationcontained herein.”

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Structured COBOL Programming, Stern &Stern, 9th edition

THE NATURE OF COBOL

COBOL is a Business-OrientedLanguageCOBOL, is one of the most widespreadcommercial applications languages in usetoday.COBOL is an abbreviation for CO mmonBusiness Oriented Language,

COBOL is a Standard LanguageCOBOL is a common programming languageavailable on most computers.

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THE NATURE OF COBOL

COBOL is an English-like Language All instructions can be coded using English words.The rules conform to many rules for writing inEnglish

COBOL is a User-Friendly LanguageBecause users are able to understand theEnglish-like instructions it is considered a user-

friendly language.

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A HISTORY OF COBOL AND THEANS VERSIONS

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WHEN IT BEGAN

Developed in 1959 by the CODASYLCommittee.

A committee consisting of representativesmembers from academia, user groups, and

computer manufacturers.Developed as a standard business-orientedlanguage for which all major manufacturerswould provide compilers.

ANS established the first standards version in1968.

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Structured COBOL Programming, Stern &Stern, 9th Edition

CHAPTER 2Cobol LanguageFundamentals

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BASIC

STRUCTURE OF ACOBOL PROGRAM

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CODING RULESThe main body of the form is subdivided into 72

positions or columns.Column 7 of a COBOL program has threeprimary purposes:1. By coding an * (asterisk) in column 7, an entire

line can be designated as a comment.2. It can be used to force the printing of

subsequent instructions on the next page of thesource listing.

3. It can be used for the continuation of nonnumericliterals.

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CODING RULES: Areas A and BPositions 8--72 of a standard COBOL programcontain program statements:

Column 8 is labeled area AColumn 12 is labeled area B

Entries in Area A, may begin in position 8, 9,10, or 11.

Most often, Area A entries begin in position 8.

If an entry is to be coded in Area B, it maybegin anywhere after position 11.

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TYPES OF COBOL ENTRIES

Divisions, sections, and paragraphs beginin Area A. Examples include:DIVISIONSIDENTIFICATION DIVISION.ENVIRONMENT DIVISION.DATA DIVISION.PROCEDURE DIVISION .

SECTIONSFILE SECTION.WORKING-STORAGE SECTION.

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TYPES OF COBOL ENTRIES

Divisions, sections, and paragraphs beginin Area A. Examples include:PARAGRAPHS

PROGRAM-ID.200-CALC-RTN.

Statements and sentences begin in AreaB; for example:SELECT PAYROLL ASSIGN TO DISK.

ADD AMT-IN TO TOTAL.

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CODING REQUIREMENTS OF THEIDENTIFICATION DIVISION

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Paragraphs in theIDENTIFICATION DIVISION

IDENTIFICATION DIVISION.PROGRAM-ID. program-name.

[AUTHOR. [comment-entry] . . .][INSTALLATION. [comment-entry] . . .][DATE-WRITTEN. [comment-entry] . . .]

[DATE-COMPILED. [comment-entry] . . .][SECURITY. [comment-entry] . . .]

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QUESTIONS?

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SELF-TEST

1. If an entry must begin in Area A, it maybegin in position _____ ;

if an entry must begin in Area B, it may beginin position _____ .

Solution: 8, 9, 10, or 11; 12, 13, 14, and so on

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SELF-TEST

2. The four divisions of a COBOLprogram must appear in order as _____

; _____ ; _____ ; and, _____ .Solution: IDENTIFICATION;

ENVIRONMENT; DATA; PROCEDURE

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SELF-TEST

3. What entries must be codedbeginning in Area A?

Solution: Division, section, andparagraph-names

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SELF-TEST

4. Most entries such as PROCEDUREDIVISION instructions are coded in

Area _____ .

Solution: B

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SELF-TEST

6. The first two entries of a COBOL programmust always be _____ and _____ .

Solution: IDENTIFICATION DIVISION.PROGRAM-ID. program-name.

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SELF-TEST

7. Each of the preceding entriesmust be followed by a _____ ,

which, in turn, must be followed by a ____ .

Solution: period; space or blank

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SELF-TEST

8. The first two entries of a program areboth coded beginning in Area _____ .

Solution: A

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SELF-TEST

9. Code the IDENTIFICATION DIVISION for aprogram called EXPENSES for a corporation,Dynamic Data Devices, Inc., written July 15,1997. This program has a securityclassification and is available to authorizedpersonnel only. It produces a weekly listing

by department of all operating expenses.

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SELF-TEST9. Suggested solution:

IDENTIFICATION DIVISION.PROGRAM-ID. EXPENSES.

AUTHOR. N. B. STERN.

INSTALLATION. DYNAMIC DATA DEVICES, INC.DATE-WRITTEN. 7/15/97.DATE-COMPILED.SECURITY. AUTHORIZED PERSONNEL ONLY.

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SELF-TEST

10. The DATE-COMPILED paragraph usuallydoes not include a comment entry because

_____ .

Solution: the computer itself can supply thedate of the compilation (The current date isstored in main memory.)

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THE SECTIONS OF THEENVIRONMENT DIVISION

The ENVIRONMENT DIVISION is the onlymachine-dependent division of a COBOLprogram.

Entries in this division will depend upon:(1) the computer system and(2) the specific devices or hardware used in theprogram.*

*Interactive programs that use keyed data as input anddisplay screen output will not need this division.

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THE CONFIGURATION SECTIONSupplies information about the computer on which

the COBOL program will be compiled and executed.SOURCE-COMPUTER:

The computer that will be used for compiling theprogram.

OBJECT-COMPUTER:- The computer that will be used for executing or

running the program.* SOURCE- COMPUTER and OBJECT-COMPUTER are

coded primarily as documentation entries.

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CONFIGURATION SECTIONEXAMPLE

ENVIRONMENT DIVISION.CONFIGURATION SECTION.

SOURCE-COMPUTER. IBM AS400.OBJECT-COMPUTER. DEC ALPHA.

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INPUT-OUTPUT SECTION

The INPUT-OUTPUT SECTION optionallyfollows the CONFIGURATION SECTION

It supplies information concerning the input and

output devices used in the program by means of aFILE-CONTROL paragraph.

In the FILE-CONTROL paragraph, a file-nameis designated and assigned to a device foreach file used in the program.

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The FILE-CONTROL paragraph consistsof SELECT statementseach is coded in Area B followed by a period.

A SELECT statement defines a file-name. assigns a device name to that file*.

A file is the major collection of data for a givenapplication.

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Batch processing applications have aninput file and an output file.Interactive processing allows input usinga keyboard;

therefore, it is not necessary to establish aninput file.

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If the output is printed or saved on disk, anoutput file must exist in the ENVIRONMENTDIVISION.

If the output is displayed on a screen, then nofile declaration is necessary in theENVIRONMENT DIVISION.- When this is the case, the ENVIRONMENT

DIVISION may be entirely omitted.

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ASSIGNING FILESTO DEVICES IN THE

ENVIRONMENTDIVISION

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OVERALL FORMAT

The instruction format for the SELECT statementfollows:

SELECT file-name-1

ASSIGN TO implementor-name-1[ORGANIZATION IS LINE SEQUENTIAL]

The implementor-name is a machine-dependent

device specification that is typically provided by thecomputer center.

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OVERALL FORMAT

File-Name Rules1. The file-name assigned to each device must

conform to the rules for forming user-definedwords.

2. A user-defined word is a word chosen by theprogrammer to represent some element in aprogram such as a file-name:

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OVERALL FORMATRules for Forming User-Defined Words (Suchas File-Names)1. 1 to 30 characters.2. Letters, digits, and hyphens (-) only.3. No embedded blanks

It is best to use hyphens to separate words (e.g.,EMPLOYEE-NAME)

4. At least one alphabetic character.

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OVERALL FORMAT

5. May not begin or end with a hyphen.6. No COBOL reserved words such asDATA, DIVISION, etc.

A full list of reserved words appears in Appendix Aand in the COBOL Syntax Reference Guide.

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OVERALL FORMAT

A SELECT statement must be specified foreach file in the program,. If a program requires a disk file as input and

produces a printed report as an output file, twoSELECT statements will be specified.

one file-name will be assigned to the disk file

the other to the print file.

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DEBUGGING TIP

File names assigned by theprogrammer should be meaningful.

Examples: SALES-INSALES-REPORT-OUT

OVERALL FORMAT

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OVERALL FORMATImplementor-Names or

Device SpecificationsMost systems enable the programmer toaccess frequently used devices by special

device names.

OVERALL FORMAT

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OVERALL FORMATImplementor-Names or

Device SpecificationsThe following are common shorthand device

specifications that you may be able to use withyour system:Printer SYSLST or SYS$OUT or

PRINTER

Disk DISC or DISK followed by adisk file-name

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SELECT Statements for PCs

1. Device SpecificationFor input or output files on disk, PC versionsof COBOL use device names that specify:(1) The drive on which the disk file appears followed

by a colon (e.g., C:, D:, etc.). If your file is in a subdirectory, you must specify thatas well (e.g., C:\COBOL).

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Structured COBOL Programming, Stern &

SELECT Statements For PCs

PC Disk files are most often created so thatthey resemble text files.This is done by using a SELECT statement

followed by:

ORGANIZATION IS LINE SEQUENTIAL.Example:SELECT SALES-FILE ASSIGN TO 'C:\SALES.DAT'

ORGANIZATION IS LINE SEQUENTIAL.

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