RPGLE Scenario-Based Interview Practice

What This Lesson Prepares You For

This lesson builds on the RPGLE Basic Interview Questions and RPGLE File I/O Interview Scenarios lessons with additional, code-reading style practice: being shown a small snippet and asked to explain what it does or find what's wrong with it, exactly the format many real interviews use.

Concepts to Revise First

• RPGLE Basic Interview Questions, and RPGLE File I/O Interview Scenarios.
• CHAIN, %FOUND, WRITE, UPDATE, and DELETE.
• The Customer Maintenance Add/Change/Delete mini project.

Common Interview or Job Discussion Scenarios

• "Here's a short RPGLE snippet. Can you tell me what it does?"
• "What would happen if this specific line were removed?"
• "Is there a bug in this code, and if so, where?"

Strong Beginner-Level Answer Approach

For code-reading questions, a strong approach is to narrate the code in order, out loud, before jumping to conclusions: what each declaration is for, then what happens on each meaningful line, then whether anything looks missing. This shows a methodical reading process rather than a guess.

Weak Answers to Avoid

• Jumping straight to "this looks fine" without actually tracing through what happens for a specific input.
• Spotting a real issue but describing it vaguely, like "something's wrong with the update," instead of naming the exact missing check or line.
• Assuming every snippet must contain a bug, when sometimes the correct answer is that the code is genuinely fine.

Scenario-Based Practice

Consider this snippet, adapted from the same shape of program as the Customer Maintenance Add/Change/Delete mini project:

dcl-f CUSTMNTD workstn;
dcl-f CUSTMAST disk keyed;

dow not exitRequested;
  exfmt MNTFMT;

  if *in03;
    exitRequested = *on;
  elseif *in05;
    chain CUSTNBR CUSTMAST;
    update CUSTMAST;
  endif;
enddo;

Practice explaining what is wrong here before reading further: the F5 branch calls CHAIN but never checks %FOUND before calling UPDATE, so entering a customer number that does not exist would cause a runtime error, exactly the mistake called out in the Customer Maintenance Add/Change/Delete mini project and the RPGLE File I/O Interview Scenarios lesson.

How to Explain Your Thinking Clearly

A useful structure for this kind of answer is: describe what the code is trying to do, name the specific missing piece, and explain what would actually happen without it. For example: "This branch is meant to update a customer after looking them up by number. It's missing a %found check between the CHAIN and the UPDATE. If the entered number doesn't match any record, UPDATE would fail at runtime, because there's no current record for it to act on."

Practical IBM i Example

elseif *in05;
  chain CUSTNBR CUSTMAST;
  if %found(CUSTMAST);
    update CUSTMAST;
  else;
    *in50 = *on;
  endif;
endif;

This is the corrected version of the snippet above: adding the %found(CUSTMAST) check before UPDATE closes the gap, and setting an error indicator in the else branch gives the user a clear message instead of letting the program fail.

Mini Practice Task

Write a short RPGLE snippet, on paper, with one deliberate bug similar to the one above, either a missing %found check or a missing keyed keyword on a dcl-f. Then explain, out loud, what would happen when the bug is triggered.

Quick Recap

• Code-reading questions reward a methodical, line-by-line narration over a quick guess.
• A missing %found check before UPDATE or DELETE is one of the most common, realistic bugs to be asked to spot.
• Naming the exact missing line, and what happens without it, is a much stronger answer than a vague "something's off."

Try Asking the AI Tutor

Use the AI Tutor to practice this format. For example, try asking:

• "Can you show me a short RPGLE snippet with a bug and ask me to find it, one snippet at a time?"
• "How would I explain, step by step, what happens when %found is skipped after a CHAIN?"