Structured COBOL Programming, Stern & Stern, 9th Edition PowerPoint Presentation: Richard H. Baum,...

Structured COBOL Programming, Stern & Stern, 9th Edition

PowerPoint Presentation:Richard H. Baum, Ph.D.DeVry Institute of Technology

9th Edition

Structured COBOL Programming

Nancy Stern Hofstra University

Robert A. Stern

Nassau Community College

“Copyright @ 2000 John Wiley & Sons, In. All rights reserved. Reproduction or translation of this work beyond that permitted in Section 117 of the 1976 United States Copyright Act without the express permission of the copyright owner is unlawful. Request for further information should be addressed to the permissions Department , John Wily & Sons, Inc. The purchaser may make back-up copies for his/her own use only and not for distribution or resale. The Publisher assumes no responsibility for errors, omissions, or damages, caused by the use of these programs or from the use of the information contained herein.”

CHAPTER 10Control Break Processing


OBJECTIVES

To familiarize you with:

1. The main types of computer-generated reports.

2. The techniques used for efficient printing of group reports and control totals.

3. Control break processing and control break printing.


CONTENTS

• An Introduction to Control Break Processing– Types of Reports: A Systems Overview

– An Example of a Control Break Procedure

• Program Requirements for Control Break Processing– A Single-Level Control Break


CONTENTS

– Refinements to Improve the Quality of a Control Break Report

– Summary of a Single-Level Control Break Procedure

– Self-Test

• Multiple-Level Control Breaks


An Introduction to Control Break Processing


An Introduction to Control Break Processing Types of Reports: A Systems Overview

• Printed Reports fall into three major categories:– Detail or Transaction Reports

– Exception Reports

– Summary Reports

• Another type of report, Displayed Output, results from interactive processing.


Detail or Transaction Reports• Detail or transaction reports are those

that include one or more lines of output for each input record read. The following are examples:– Customer bills generated from a master

accounts receivable file would be an example of a transaction or detail report.

– Payroll checks generated from a master payroll file would be a detail report.

– A listing of each part number stocked by a company would be a detail report.


Detail or Transaction Reports• Transaction or detail output is

produced when information for each input record is required.

• Because detail reports generate output for each input record read, they can take a relatively long time to produce. – Printing 300,000 checks from a file of

300,000 records, for example, could take several hours.


Exception ReportsA listing of those clients with overdue

balances is an example of an exception report.

• An exception report is any printout of individual records that meet (or fail to meet) certain criteria. Other examples of exception reports are:

– A list of employees who are 65 years old or older.

– A list of part numbers in stock with a quantity on hand below some minimum value.


Summary Reports

As the name suggests, a summary or group report summarizes rather than itemizes.

• Often summaries or totals can provide more comprehensive and meaningful information for the user than a detail or exception report.


Displayed Output: A Systems Overview Interactive Processing. When output is required as responses

to inquiries and where printed copies are not needed, displayed output is often used.

The output is generated on a screen quickly and there is no need to generate paper, this can be costly and burdensome to store.


Displayed Output: A Systems Overview

Generally, detail and summary reports appear in printed form; short exception report s are often displayed on a monitor.

• Displayed output must be clear, concise and informative just like printed output.

• We use a DISPLAY verb to generate output on a screen.– There is no need to establish an output file

for output that will be displayed.


PROGRAM REQUIREMENTS FOR CONTROL BREAK PROCESSING

This chapter considers a type of summary procedure called control break processing.

With this type of processing, control fields are used to indicate when totals are to print.


A Single-Level Control Break

Control Break Processing is when a field (known as the key or control field) changes from one record to the next.

When this change takes place then the following takes place:

An appropriate control total line is printed.

The appropriate control field is initialized.

The appropriate control total is initialized.


Control Break Processing: a Modular, Top-Down MAIN MODULE

You may wish to examine Figure 10.2 in your textbooks for the pseudocode planning tool used to prepare the program.

The program that will perform this control break procedure is shown in Figure 10.3 (The hierarchy chart is shown in Figure 10.4).Excerpts follow.


Control Break Processing: a Modular, Top-Down ApproachThe Main module is subdivided into

subordinate modules that perform:

1. initializing functions

2. heading functions

3. calculations

4. end-of-job procedures

Helps focus on design and structure

Easier to debug


A Modular, Top-Down ApproachPseudocode Excerpt

MAIN-MODULE

PERFORM Initialize-Rtn

PERFORM Heading-Rtn

PERFORM UNTIL there is no more input

READ a Record

NOT AT END PERFORM Detail-Rtn

AT END Move 'NO ' to Are-There-More-Records

END-READ

END-PERFORM


Program Excerpt100-MAIN-MODULE.

PERFORM 500-INITIALIZATION-RTN

PERFORM 400-HEADING-RTN

PERFORM UNTIL ARE-THERE-MORE-RECORDS = 'NO '

READ SALES-IN

AT END

MOVE 'NO ' TO ARE-THERE-MORE-RECORDS

NOT AT END

PERFORM 200-DETAIL-RTN

END-READ

END-PERFORM...


A Modular, Top-Down Approach

Program Excerpt

...

500-INITIALIZATION-RTN.

OPEN INPUT SALES-IN

OUTPUT PRINT-OUT.


200-DETAIL-RTN

The processing of input records at 200-DETAIL-RTN depends on whether there is a change in control fields, which we call a control break.

EVALUATE accomplishes two things:

1. Determines if the record being processed is the first one.

2. Initializes WS-HOLD-DEPT with that record’s DEPT-IN control field.


200-DETAIL-RTNProgram Excerpt200-DETAIL-RTN.

EVALUATE TRUEWHEN FIRST-RECORD = 'YES'

MOVE DEPT-IN TO WS-HOLD-DEPT

MOVE 'NO ' TO FIRST-RECORD

WHEN DEPT-IN NOT = WS-HOLD-DEPTPERFORM 300-CONTROL-BREAK

END-EVALUATE

IF WS-LINE-CT > 25PERFORM 400-HEADING-RTN

END-IF


200-DETAIL-RTN (Continued)200-DETAIL-RTN.

MOVE DEPT-IN TO DL-DEPT-OUT

MOVE SLSNO-IN TO DL-SLSNO-OUT

MOVE AMT-OF-SALES-IN TO DL-AMT-OF-SALES-OUT

WRITE PRINT-REC FROM DETAIL-LINE AFTER ADVANCING 2 LINES

ADD 1 TO WS-LINE-CT

ADD AMT-OF-SALES-IN TO WS-DEPT-TOTAL.


300-CONTROL-BREAK

In the 300-CONTROL-BREAK module we print a summary line after a record is read that has a different department number than the one stored at WS-HOLD-DEPT.

300-CONTROL-BREAK is performed when an input record's DEPT-IN, the control field, differs from the one stored at WS-HOLD-DEPT.


300-CONTROL-BREAK

When there is a change in DEPT-IN, we must:

1. Print a line with the department total accumulated for the previous DEPT-IN control group, which is stored in WS-DEPT-TOTAL.

2. Reinitialize WS-DEPT-TOTAL, the control total, so that the next department's total begins at zero before any amounts for the new control group have been accumulated.


300-CONTROL-BREAK

3. Move the current DEPT-IN to WS-HOLD-DEPT so that we can compare succeeding input records to this new DEPT-IN control field.

4. Return to 200-DETAIL-RTN and process the current record by printing a detail line and adding the amount to the control total.


300-CONTROL-BREAK

Program Excerpt

300-CONTROL-BREAK.

WRITE PRINT-REC FROM GROUP-REC

MOVE WS-DEPT-TOTAL TO DEPT-TOTAL-OUT AFTER ADVANCING 2 LINES

ADD 1 TO WS-LINE-CT

MOVE ZEROS TO WS-DEPT-TOTAL

MOVE DEPT-IN TO WS-HOLD-DEPT.


Forcing a Control Break When There Are No More Records Control break printing of totals occurs

when:

A record with a new control field is read.

The total for the last group of records, then, will have been accumulated when ARE-THERE-MORE-RECORDS is equal to 'NO '.

A control total will not have been printed since there is no subsequent record to trigger a change.


Forcing a Control Break When There Are No More RecordsDEPT

01 01 01 02 --- 01 totals are printed when 02 is read

02 03 --- 02 totals are printed when 03 is read 03

(no more records)

At this point, the printing of 03 totals must be ``forced'' after ARE-THERE-MORE-RECORDS is set equal to 'NO '


Forcing a Control Break When There Are No More RecordsWe need to include a procedure to print

the 03 totals.

In the main module, after 200-DETAIL-RTN has been repeatedly executed and ARE-THERE-MORE-RECORDS is equal to 'NO '.

We must return to the statement following the in-line PERFORM ... END- PERFORM and force a printing of this final total.


REFINEMENTS TO IMPROVE THE QUALITY OF A CONTROL BREAK REPORT


Printing a Final Total

Sometimes, control break processing also requires the printing of a summary line containing a final total.

This summary line (with final total) would be printed after the last control total is written.


Printing a Final TotalMethod 1

The final total, which we will call WS-FINAL-TOTAL, may be accumulated by adding AMT-OF-SALES-IN for each record.

This may be accomplished by changing the ADD instruction in the 200- DETAIL-RTN to:

ADD AMT-OF-SALES-IN TO WS-DEPT-TOTAL WS-FINAL-TOTAL


Printing a Final TotalMethod 2The WS-FINAL-TOTAL may be

accumulated, instead, by adding each WS-DEPT-TOTAL to it in 300-CONTROL-BREAK.

This means that WS-FINAL-TOTAL would be accumulated, not for each detail record, but only when a control break has occurred.


Printing a Final TotalMethod 2This would be accomplished by coding

the following before we reinitialize WS-DEPT- TOTAL:

300-CONTROL-BREAK.

...

ADD WS-DEPT-TOTAL TO WS-FINAL-TOTAL


...


Starting a New Page After Each Control BreakIt is likely that separate pages of a

control break report will be distributed to different users.

In this case, it is useful to have each department's data begin on a new page.

Thus, a control break module would also include a statement to PERFORM the heading routine so that the paper is advanced to a new page when a control break occurs.


Starting a New Page After Each Control Break

We would add a PERFORM statement to the 300-CONTROL-BREAK module for printing headings on a new page each time that module is executed.

In this instance, it would be redundant to print the Department Number on each detail line. Rather, it would be better to print it once at the beginning of each page as a page heading.


Sequence-Checking or Sorting

For accurate control break processing, records must be in sequence by the control field.

It might be useful to check to make certain, after each control break, that no sequence error occurred. If one did, an error message should be printed.


Executing the Control Break Module from the Main Module After an End-of-File Condition Has Been MetIf we wish to “force” a control

break at the end of the job, it is best to perform the sequence of steps in the control break routine.


SUMMARY OF STEPS INVOLVED IN A SINGLE-LEVEL CONTROL BREAK PROBLEM1. For the first record read, move the

control field to a hold area in WORKING-STORAGE.

2. For each additional record, as long as the control field is equal to the hold area, execute the detail routine for the input record. This means: Add the appropriate amount

to a control total, print the detail record (if desired), and read the next record.


SUMMARY OF STEPS INVOLVED IN A SINGLE-LEVEL CONTROL BREAK PROBLEM3. If, for a specific record read, the

control field is not equal to the hold area:

Print the control total.

Initialize the control total field to zero.

Reinitialize the hold field with the new control field value if ARE- THERE-MORE-RECORDS is not equal to 'NO '.


SUMMARY OF STEPS INVOLVED IN A SINGLE-LEVEL CONTROL BREAK PROBLEM

Process the detail record as in step 2.

Print headings on a new page if each control total is to appear on a separate page.

4. After all records have been processed, perform a control break to print the last control group.


QUESTIONS?


SELF-TEST

1. In control break processing, we typically MOVE the control field to ____ after reading the first record (when FIRST-RECORD = 'YES').

Solution: a hold or WORKING-STORAGE area


SELF-TEST

2. What processing is performed if an input control field is equal to the control field stored in the hold area?

Solution: We add to a control total and print, if detail printing is required.


SELF-TEST

3. What processing is performed if an input control field is not equal to the control field stored in the hold area?

Solution: We perform a control break procedure.


SELF-TEST

4. If each control group is to begin on a separate page, we would perform a heading routine at the ____ module.

Solution: control break


SELF-TEST

5. If a final total is required, it is most efficient to accumulate the final total in the ____ module.

Solution: control break


SELF-TEST

6. At the control break module, we must print ____ , initialize ____ at zero, and move ____ .

Solution: the control total; the control total; the input control field to the hold area


SELF-TEST

7. When each individual input record results in the printing of an output line, we call this ____ .

Solution: detail or transaction printing


Multiple-Level Control Breaks

•When two or more fields are required as control fields:

– Use a double-level control break

– Need two holding areas for comparison purposes.


Multiple-Level Control BreaksSample Input DataDEPT-IN SLSNO-IN AMT-OF-TRANS-IN

01 001* 34555

01 001* 54434

01 002* 65544

01 003* 76353

02 001* 09377

02 001* 92838

02 002* 09374

02 002* 09383 * in sequence by department number


Multiple-Level Control BreaksSample OutputMONTHLY SALES REPORT PAGE 1

01/29/2001

DEPT-01

SALESPERSON NUMBER TOTAL AMT OF SALES

001 $889.89

002 $655.44

003 $763.53

TOTAL FOR DEPT - $2,308.86


Multiple-Level Control BreaksSample OutputMONTHLY SALES REPORT PAGE 2

01/29/2001

DEPT-02

SALESPERSON NUMBER TOTAL AMT OF SALES

001 $1,022.15

002 $187.57

TOTAL FOR DEPT - $1,209.72


Multiple-Level Control BreaksProgram Excerpt

100-MAIN-MODULE.

PERFORM 600-INITIALIZATION-RTN.

PERFORM UNTIL NO-MORE-RECORDS

READ TRANS-FILE-IN

AT END

MOVE 'NO ' TO ARE-THERE-MORE- RECORDS

NOT AT END

PERFORM 200-DETAIL-RTN

END-READ

END-PERFORM.


Multiple-Level Control BreaksProgram Excerpt600-INITIALIZATION-RTN.

OPEN INPUT TRANS-FILE-IN

OUTPUT REPORT-FILE-OUT

ACCEPT WS-DATE FROM DATE

.

.

.


Multiple-Level Control BreaksProgram ExcerptNo Detail printing required, no write

needed:

200-DETAIL-RTN.

EVALUATE TRUE

WHEN FIRST-RECORD = 'YES'MOVE SLSNO-IN TO WS-HOLD-SLSNOMOVE DEPT-IN TO WS-HOLD-DEPTPERFORM 500-HEADING-RTNMOVE 'NO ' TO FIRST-RECORD


Multiple-Level Control BreaksProgram Excerpt

WHEN DEPT-IN NOT = WS-HOLD-DEPT

PERFORM 400-DEPT-BREAK

WHEN SLSNO-IN NOT = WS-HOLD-SLSNO

PERFORM 300-SLS-BREAK

END EVALUATE

ADD AMT-OF-TRANS-IN TO WS-SLS-TOTAL.


Multiple-Level Control BreaksProgram Excerpt400-DEPT-BREAK.

PERFORM 300-SLS-BREAK

MOVE WS-DEPT-TOTAL TO DL-DEPT- TOTAL

WRITE REPORT-REC-OUT FROM DL-DEPT-LINE AFTER

ADVANCING 2 LINES


Multiple-Level Control BreaksProgram Excerpt400-DEPT-BREAK. (continued)

IF MORE-RECORDS




END-IF.


MULTIPLE-LEVEL CONTROL BREAKS• The last WHEN condition tested in

EVALUATE is the minor-level control break. – This test is performed only if FIRST-RECORD

is not equal to 'YES' (for all records except the first) and if there is no major control break.

• When a change in SLSNO-IN occurs even without a change in DEPT-IN, this would force a minor control break called 300-SLS-BREAK.


MULTIPLE-LEVEL CONTROL BREAKS

• Thus, when SLSNO-IN is not equal to WS-HOLD-SLSNO (or when a department break has occurred) we do the following:

1. Print the total for the previous SLSNO-IN.

2. Add that total to a WS-DEPT-TOTAL.

3. Initialize the WS-SLS-TOTAL field at zero.

4. Move the new SLSNO-IN to WS-HOLD-SLSNO.


Multiple-Level Control BreaksProgram Excerpt300-SLS-BREAK.

MOVE WS-SLS-TOTAL TO DL-SLS-TOTAL

MOVE WS-HOLD-SLSNO TO DL-SLSNO

WRITE REPORT-REC-OUT FROM DL-SLS-LINE AFTER ADVANCING 2 LINES

ADD WS-SLS-TOTAL TO WS-DEPT-TOTAL

IF MORE-RECORDSMOVE ZERO TO WS-SLS-TOTAL

MOVE SLSNO-IN TO WS-HOLD-SLSNO

END-IF.


Multiple-Level Control BreaksProgram Excerpt• Once all records have been read and

processed and an AT END condition occurs, control returns to the main module, where an end-of-job routine is executed.

300-SLS-BREAK.

. . .

IF MORE-RECORDSMOVE ZERO TO WS-SLS-TOTALMOVE SLSNO-IN TO WS-HOLD-SLSNO

END-IF.


Multiple-Level Control BreaksProgram Excerpt400-DEPT-BREAK.

.

.

IF MORE-RECORDS




END-IF.


DEBUGGING TIP• When programs start to get complex with

numerous procedures, programmers sometimes lose sight of the relationships among modules.

• This is where hierarchy charts can be helpful.– Note, too, that the PIC clause for the control field

in the input record must be exactly the same as the PIC clause for the hold area that stores a control field.• If they are not the same, the comparison performed

to test for a control break could result in errors.


CHAPTER SLIDES END HERE

CHAPTER SUMMARY COMES NEXT


CHAPTER SUMMARY• A PROCEDURE DIVISION shell like the

one found in the chapter summary of your text can be useful for processing any number of control breaks within a program.

• Control Break Routines:– Higher-level breaks force lower-level breaks.

– Appropriate control total line is printed.

– Appropriate control field is initialized.

– Appropriate control total is initialized.


CHAPTER SUMMARY

• In a control break program, all input records must be in sequence by minor control fields within intermediate control fields within major control fields.

• If the records are not already in this order, then the file must be sorted into the required sequence before it can be processed.

Structured COBOL Programming, Stern & Stern, 9th Edition PowerPoint Presentation: Richard H. Baum,...

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