EVALUATE: The Decision Table

COBOL GnuCOBOL 3.2.0 · ✓ verified by execution on 2026-08-16

When programs require complex conditional logic, nested IF-ELSE statements can quickly become difficult to read. Mainstream languages like C, Java, and JavaScript introduced the switch statement to handle this.

COBOL introduced the EVALUATE statement in 1985. It serves the same purpose as a switch statement but is significantly more powerful.

The Basic EVALUATE

In its simplest form, EVALUATE checks a single variable against multiple potential values using WHEN clauses. The WHEN OTHER clause acts as the default fallback if no preceding condition is met.

       IDENTIFICATION DIVISION.
       PROGRAM-ID. EVAL-BASIC.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01 HTTP-STATUS PIC 999 VALUE 404.
       PROCEDURE DIVISION.
           EVALUATE HTTP-STATUS
               WHEN 200
                   DISPLAY 'OK'
               WHEN 404
                   DISPLAY 'NOT FOUND'
               WHEN 500
                   DISPLAY 'SERVER ERROR'
               WHEN OTHER
                   DISPLAY 'UNKNOWN STATUS'
           END-EVALUATE.
           STOP RUN.

Output

NOT FOUND

Your output

No Fall-Through

If you have experience with C, C++, or Java, you are likely familiar with the concept of “fall-through.” In those languages, if you omit a break statement at the end of a case, execution blindly continues into the next case.

COBOL does not have fall-through. Once a WHEN clause is matched and its instructions are executed, control immediately jumps to END-EVALUATE.

Predict the output cobol

Read the code. What exactly will it print? Commit to an answer before you look.

       IDENTIFICATION DIVISION.
       PROGRAM-ID. EVAL-FALL.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01 LOG-LEVEL PIC X VALUE 'W'.
       PROCEDURE DIVISION.
           EVALUATE LOG-LEVEL
               WHEN 'W'
                   DISPLAY 'WARNING'
               WHEN 'E'
                   DISPLAY 'ERROR'
           END-EVALUATE.
           DISPLAY 'DONE'.
           STOP RUN.

Output

WARNING
DONE

You predicted

A novice coming from C might expect this to output WARNING, ERROR, and DONE because there is no break statement. However, in COBOL, the EVALUATE statement automatically exits the block after executing the matched WHEN clause!

EVALUATE TRUE: The Decision Table

The most celebrated feature of COBOL’s EVALUATE statement is EVALUATE TRUE.

Instead of passing a variable to EVALUATE, you pass the boolean literal TRUE. This allows each WHEN clause to be an entirely independent boolean expression, functioning like a clean IF-ELSE-IF chain.

       IDENTIFICATION DIVISION.
       PROGRAM-ID. EVAL-TRUE.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01 AGE PIC 99 VALUE 70.
       PROCEDURE DIVISION.
           EVALUATE TRUE
               WHEN AGE < 13
                   DISPLAY 'CHILD'
               WHEN AGE >= 13 AND AGE < 20
                   DISPLAY 'TEENAGER'
               WHEN AGE >= 65
                   DISPLAY 'SENIOR'
               WHEN OTHER
                   DISPLAY 'ADULT'
           END-EVALUATE.
           STOP RUN.

Output

SENIOR

Your output

Because EVALUATE exits upon the first match, order matters. The conditions are evaluated top-to-bottom. If AGE is 70, the first two conditions evaluate to FALSE. The third evaluates to TRUE, executes DISPLAY 'SENIOR', and then drops out of the EVALUATE block.

Visualization: The Evaluation Flow

Here is a visual representation of how EVALUATE TRUE cleanly routes execution. Notice how it exits immediately after a match, avoiding the spaghetti flow of nested IF statements.

Check yourself

How does the EVALUATE statement handle fall-through?

Reveal answer

It never falls through; once a WHEN clause executes, control jumps to END-EVALUATE. — COBOL's EVALUATE implicitly breaks after a match. There is no fall-through mechanism.

What is the purpose of EVALUATE TRUE?

Reveal answer

It allows testing of completely independent boolean conditions in each WHEN clause. — EVALUATE TRUE acts as a highly readable alternative to nested IF-ELSE structures, treating each WHEN clause as an independent boolean test.

If the first two WHEN clauses in an EVALUATE block evaluate to TRUE, which ones execute?

Reveal answer

Only the first one executes. — COBOL EVALUATE exits immediately after the very first matched WHEN clause. Subsequent matches are never evaluated.

Challenges

Challenge 1 +20 XP

Write a basic EVALUATE that checks the COMMAND variable. If it is 'START', display 'SYSTEM BOOTING'. If it is 'STOP', display 'SYSTEM HALTED'. For any other command, display 'INVALID COMMAND'.

COBOL has no in-browser runtime, so this one is pen-and-paper: work out what the fixed code should be, then open the solution and compare. The expected output below is real — it came from compiling the solution with GnuCOBOL when this page was built.

Test 1 — expects "SYSTEM HALTED\n"

Need a hint? (−25% XP)

Use `WHEN 'START'` and `WHEN 'STOP '`. Use `WHEN OTHER` for the invalid command case.

Show solution (0 XP)

IDENTIFICATION DIVISION.
PROGRAM-ID. CMD-TEST.
DATA DIVISION.
WORKING-STORAGE SECTION.
01 COMMAND PIC X(5) VALUE 'STOP '.
PROCEDURE DIVISION.
    EVALUATE COMMAND
        WHEN 'START'
            DISPLAY 'SYSTEM BOOTING'
        WHEN 'STOP '
            DISPLAY 'SYSTEM HALTED'
        WHEN OTHER
            DISPLAY 'INVALID COMMAND'
    END-EVALUATE.
    STOP RUN.

Challenge 2 +20 XP

Convert this logic to use EVALUATE TRUE. If SCORE is 90 or above, display 'A'. If 80 or above, display 'B'. Otherwise, display 'C'.

Test 1 — expects "B\n"

Need a hint? (−25% XP)

Use `WHEN SCORE >= 90`, then `WHEN SCORE >= 80`, and finally `WHEN OTHER`.

Show solution (0 XP)

IDENTIFICATION DIVISION.
PROGRAM-ID. GRADE-TEST.
DATA DIVISION.
WORKING-STORAGE SECTION.
01 SCORE PIC 99 VALUE 85.
PROCEDURE DIVISION.
    EVALUATE TRUE
        WHEN SCORE >= 90
            DISPLAY 'A'
        WHEN SCORE >= 80
            DISPLAY 'B'
        WHEN OTHER
            DISPLAY 'C'
    END-EVALUATE.
    STOP RUN.