Easytrieve Control Flow Overview

Sequential Default Versus Branching

Easytrieve executes statements in source order within an activity unless a control flow statement redirects. JOB INPUT loops imply read-process-print per record, but IF STATUS EQ 'D' can skip PRINT for deleted rows. DO WHILE IDX LE OCCURS-MAX walks array slots without unrolling MOVE statements. Understanding default sequential flow clarifies what IF and GOTO interrupt.

Decision Family — IF, ELSE-IF, ELSE

One END-IF closes the entire IF/ELSE-IF/ELSE group. ELSE-IF does not get its own END-IF. Nested IF requires an END-IF per nested IF. Chapter pages on IF and ELSE expand condition catalogs—EOF, MATCHED, DUPLICATE, field class tests—and contrast nesting with ELSE-IF chains.

Loop Family — DO WHILE, DO UNTIL, WHILE, UNTIL

Executable syntax is always DO WHILE or DO UNTIL ... END-DO. Tutorial indexes list WHILE and UNTIL as separate pages because developers search those terms. DO WHILE is top-tested—zero iterations possible. DO UNTIL is bottom-tested—at least one iteration. No counted DO n TIMES; build counters with INDEX or numeric fields inside the body. Loops chapter page ties WHILE, UNTIL, and nested patterns together.

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DO WHILE IDX LE MAX-SLOTS
  IF SLOT-FLAG(IDX) EQ 'Y'
    PROCESS-SLOT
  END-IF
  IDX = IDX + 1
END-DO

Multi-Way Choice — CASE and SELECT

CASE evaluates an expression and runs labeled WHEN branches—useful for status code dispatch. SELECT in control flow context (distinct from sort SELECT) handles other multi-path patterns per release documentation. Both reduce deep ELSE-IF ladders when values are discrete. Read CASE and SELECT chapter pages after mastering IF.

Jumps — GOTO, EXIT, RETURN

GOTO after END-DO exits loops when no BREAK exists. Overuse obscures logic—prefer IF and structured ELSE-IF when maintainers read your code. EXIT in sort BEFORE procedures ends prescreen without SELECT. RETURN pairs with PROC called from PERFORM-style flows.

Control Flow in Activities

• JOB — IF on file fields after GET; DO for array walks; GOTO JOB to skip remaining records.
• PROGRAM — Shared decision logic across multiple JOB names; RETURN from procedures.
• SCREEN — IF on PF keys and field validation; DO for repeating screen rows.
• SORT BEFORE — IF with SELECT or EXIT; restricted statement set per sort prescreen rules.
• Report procedures — IF in BEFORE-LINE; DO rare for generated lines.

Chapter Learning Path

1. Control flow overview (this page) — map the territory.
2. IF — conditions, nesting, ELSE-IF versus nested IF.
3. ELSE — catch-all false branch semantics.
4. DO — WHILE versus UNTIL, END-DO, infinite loops.
5. WHILE — top-tested loops in depth.
6. UNTIL, CASE, SELECT, Loops, EXIT, RETURN — complete the toolbox.

Statements Reference Versus Chapter Pages

Statements under /statements/if document Language Reference syntax for the IF verb. Chapter pages under /control-flow/if emphasize how IF fits JOB editing, audit tallies, and GOTO bypass patterns in beginner batch programs. Read both: reference for compile rules, chapter for job context.

Common Control Flow Mistakes

Explain It Like I'm Five

Control flow is how the computer chooses what to do next. IF is a fork in the path: if it is raining, take the umbrella branch; otherwise keep walking. ELSE is the otherwise branch. DO is a merry-go-round: keep spinning while the music plays (WHILE), or spin until the bell rings (UNTIL). GOTO is jumping to a different spot on the playground when you are done with the merry-go-round early. Activities like JOB are different playgrounds; control flow is the rules on each playground.

Exercises

1. Label decision versus loop statements in a sample JOB excerpt.
2. Draw flowchart for IF / ELSE-IF / ELSE / END-IF with three grade bands.
3. Explain when DO UNTIL beats DO WHILE for read-then-test file logic.
4. List five valid IF condition types from Broadcom documentation.
5. Map which chapter page you would read next for multi-way status dispatch.