Mini Project: Printer File Report with Totals

What We Are Building

RPT002R, an order history report listing every order grouped by customer, printing a subtotal each time the customer changes, and a final grand total at the end, combining the Batch Report Program mini project's grand total with the control-break pattern from the Controlling Page Breaks lesson.

Business Scenario

The Batch Report Program mini project produced one flat list with a single grand total. Accounting now wants to see each customer's orders grouped together, with that customer's own subtotal clearly shown before moving on to the next customer, still finishing with an overall grand total.

Concepts Used

• Report record formats and totals, from the Report Record Formats and Report Totals and Summary Lines lessons.
• The control-break pattern, from the Controlling Page Breaks lesson, used here to trigger a subtotal rather than a forced new page.
• Native READ and %EOF over ORDHIST, already keyed by customer number.

Files and Programs Involved

• ORDHIST, read from beginning to end, naturally in customer order since it is keyed by CUSTNBR.
• RPT002P, a new printer file with four record formats: HDGFMT, DTLFMT, SUBFMT (customer subtotal), and TOTFMT (grand total).
• RPT002R, the RPGLE program producing the report.

Step-by-Step Build Outline

1. Design RPT002P's four record formats: heading, one order detail line, one customer subtotal line, and one grand total line.
2. Declare RPT002P and ORDHIST in RPT002R.
3. Write HDGFMT once before the loop.
4. Loop with native READ and %EOF, comparing each record's CUSTNBR against the previous one, exactly the control-break detection covered in the Controlling Page Breaks lesson.
5. When the customer number changes, print that customer's subtotal with SUBFMT, then reset the subtotal accumulator before continuing.
6. Accumulate both the customer subtotal and the grand total on every detail line.
7. After the loop ends, print the final customer's subtotal, then the grand total with TOTFMT.

Example Code

dcl-f RPT002P printer;
dcl-f ORDHIST disk keyed;

dcl-s prevCustNbr packed(6:0) inz(0);
dcl-s custSubtotal packed(9:2) inz(0);
dcl-s grandTotal packed(11:2) inz(0);

write HDGFMT;

read ORDHIST;
dow not %eof(ORDHIST);
  if CUSTNBR <> prevCustNbr and prevCustNbr <> 0;
    write SUBFMT;
    custSubtotal = 0;
  endif;

  write DTLFMT;
  custSubtotal += ORDAMT;
  grandTotal += ORDAMT;
  prevCustNbr = CUSTNBR;

  read ORDHIST;
enddo;

write SUBFMT;
write TOTFMT;

*inlr = *on;

Here, the control-break check is exactly the pattern covered in the Controlling Page Breaks lesson, but instead of forcing a new page, it prints SUBFMT for the customer that just finished and resets custSubtotal back to zero. grandTotal accumulates across every order regardless of customer, and is never reset. After the loop ends, one final write SUBFMT; prints the last customer's subtotal, since the control-break check inside the loop only catches a change between two different customers, not the very last one.

How to Test It

Run against a small, known set of orders across two or three customers, confirming each customer's subtotal matches a manual sum of their own orders, and the final grand total matches the sum of every order across every customer.

Common Mistakes

• Forgetting the final write SUBFMT; after the loop ends, leaving the last customer's subtotal missing from the report entirely.
• Resetting custSubtotal before printing SUBFMT instead of after, which would print a subtotal of zero instead of the actual amount.
• Accidentally resetting grandTotal alongside custSubtotal, losing the running total across customers.

Debugging Checklist

If a customer's subtotal looks wrong, follow the Report Totals and Summary Lines lesson's guidance: set a breakpoint on the write SUBFMT; line and use EVAL on custSubtotal to confirm it holds the expected sum at exactly the moment the customer changes.

Possible Extensions

A natural extension is adding a count of orders per customer alongside the amount subtotal, accumulating a second counter variable the same way custSubtotal is accumulated, exactly the multiple-running-totals pattern covered in the Report Totals and Summary Lines lesson.

Quick Recap

• RPT002R combines a control break with running totals, printing a subtotal each time the customer changes and a grand total at the end.
• The final customer's subtotal needs its own write SUBFMT; after the loop, since the control break only fires on a change between two different customers.
• Testing against a small, known set of orders lets you verify subtotals and the grand total by hand.

Try Asking the AI Tutor

Use the AI Tutor to practice extending or troubleshooting this project. For example, try asking:

• "How would I add an order count alongside the amount subtotal for each customer?"
• "What would this report look like if the final write SUBFMT after the loop were accidentally left out?"