RPGLE Program Calling a Display File

Learning Objective

By the end of this lesson, you will be able to declare a display file in free-format RPGLE using dcl-f, and use exfmt to show a record format and read back what the user entered.

Simple Explanation

You now understand what a display file is, how its record formats and fields work, and how function keys tie to indicators. This lesson connects all of that to actual RPGLE code, showing how a program works with a display file.

A display file is declared in free-format RPGLE using dcl-f, the same keyword used to declare other kinds of files, with the special keyword workstn identifying it as a workstation file:

**free
ctl-opt dftactgrp(*no);

dcl-f CUSTINQD workstn;

dcl-s exitRequested ind;

dow not exitRequested;
  exfmt INQFMT;

  if *in03;
    exitRequested = *on;
  endif;
enddo;

*inlr = *on;

Here, dcl-f CUSTINQD workstn; declares CUSTINQD as the display file this program works with. The exfmt operation shows a specific record format, INQFMT here, and then waits for the user to respond, in one combined step: it writes the format to the screen and reads back whatever the user entered once they submit it. After exfmt returns, the program checks *in03, the indicator tied to F3 as covered in the Function Keys and Response Indicators lesson, deciding whether to exit the loop.

Why It Matters

exfmt is the core operation connecting an RPGLE program to a 5250 screen: it is how a program actually shows something to the user and gets their response back, all in a single step. Understanding dcl-f and exfmt together explains, at a code level, exactly how the display file concepts covered earlier in this lesson group connect to a real, running RPGLE program.

Practical Example

Imagine the customer inquiry program described throughout this lesson group. It declares CUSTINQD as its display file, then repeatedly calls exfmt INQFMT inside a loop: each time, the screen appears, the user either enters a customer number or presses F3 to exit, and the program checks *in03 to decide whether to keep looping or stop. This is exactly the shape of a simple, interactive 5250 program.

This is a simplified, illustrative example rather than a specific real program, but it reflects the core pattern behind many interactive 5250 RPGLE programs.

Common Confusions

"Is exfmt the same as separately writing a screen and then reading it?" exfmt combines both steps, showing the format and reading the user's response, into one operation. This lesson focuses on exfmt specifically because it is the most common, straightforward way beginners work with display files; separate write and read operations exist but are a more detailed topic beyond this introductory lesson.

"Does dcl-f work the same way for display files as for other kinds of files?" dcl-f is used to declare any kind of file in free-format RPGLE, but the keyword workstn specifically identifies a workstation file, such as a display file, telling the compiler to expect this particular kind of interactive file rather than a physical or logical file.

"What happens if the user enters something in the customer number field before exfmt returns?" Whatever the user typed into an input or both field, as covered in the Input Fields, Output Fields, and Both Fields lesson, becomes available to the RPGLE program as soon as exfmt returns, ready to be used in the program's logic, such as looking up that customer.

Quick Recap

• A display file is declared in free-format RPGLE using dcl-f fileName workstn;.
• exfmt formatName; shows a record format to the user and reads back their response in a single operation.
• After exfmt returns, the program can check relevant indicators, such as *in03, to see which function key the user pressed.
• dcl-f and exfmt together are the core building blocks connecting an RPGLE program to a 5250 screen.

Try Asking the AI Tutor

Use the AI Tutor to ask follow-up questions about this lesson. For example, try asking:

• "What is the difference between exfmt and using separate write and read operations?"
• "Can one RPGLE program use more than one display file?"