cobol — consolidated language guide — DedSec Project

COBOL

Typical use: Historical and enterprise languages.

Suggested file extension: .cob.

How to run / environment: cobc -x -free hello.cob && ./hello.

Starter example

identification division.
program-id. hello.
procedure division.
    display "Hello, Ada!".
    stop run.

How to read it

COBOL remains significant in business systems.

Common pitfall

COBOL remains significant in business systems.

COBOL — Expanded practice workbook

Inspect the smallest source

identification division.
program-id. hello.
procedure division.
    display "Hello, Ada!".
    stop run.

Run or compilation context: cobc -x -free hello.cob && ./hello.. Treat this as a baseline: save a copy, confirm the toolchain version and note whether the example merely evaluates a value, prints text, or creates external effects. Production accounts, datasets and hardware must not be used for first attempts.

Work through the actual mechanism

Create a fixed-width customer record with PIC fields, validate a numeric amount and produce a totals report. Compare edited picture clauses with stored numeric representation.

Diagnose the sharp edge

Column format, decimal settings and packed numeric fields differ by compiler and file conventions. Preserve fixtures before conversion.

COBOL — Focused mastery pathway

Learn the memory and execution model

Create a fixed-format or free-format COBOL program (state the format) containing a PIC 9(5)V99 amount and a displayed edited amount. Trace stored value separately from displayed punctuation.

Deliberate failure and corrective experiment

Read three fixed-width input records in a scratch directory, rejecting unexpected record lengths and nonnumeric amount data before adding totals. Inspect FILE STATUS rather than assuming successful OPEN/READ.

Independent engineering assignment

Implement a small customer balance report with a test copybook defining the shared record layout. Test missing file, all-zero balance, and large amount; compare decimal precision with float-based calculations.