01 — divisions
A COBOL program is paperwork: identity, environment, data, then procedure — structure by bureaucracy.
IDENTIFICATION DIVISION.
ENVIRONMENT DIVISION.
DATA DIVISION.
PROCEDURE DIVISION.§ 02 — Eras · 1959
COBOL
business English that never retired
Left: era context, features, and the 101 hello. Right: 3 core concepts, 3 deeper 201 lessons, the factorial specimen, and where COBOL lives today — each column scrolls on its own.
The problem it solves
Every vendor’s machine processed business data differently, and programs were unreadable to management. COBOL standardized both.
The problem it carries
Verbosity beyond parody — and it worked so well that billions of lines are still running, long after anyone could fully explain how.
Key features
- the record
- Fixed-layout fields described with PICTURE clauses — data specified before the logic that uses it.
- english-like verbs
- MOVE, ADD, DISPLAY: a hundred English words that read like a procedure in a manual.
- divisions
- Identification, environment, data, procedure — a program organized like a bound document.
- the portability mandate
- One standard enforced across vendors by the DoD — the reason it outlived every rival.
101 — hello, world
Session one is the smallest program that still counts as speaking COBOL: what every tutorial prints first, in the dialect that mattered when the language arrived (1959).
IDENTIFICATION DIVISION.
PROGRAM-ID. HELLO.
PROCEDURE DIVISION.
DISPLAY "Hello, world".
STOP RUN.101First contact — hello world and 3 ideas that define how COBOL reads. 201 — 3 lessons on mechanisms you meet after the factorial specimen: the sharp edges practitioners actually use.
101 — core concepts
3 fragments, each naming a habit of mind in COBOL. Read the note, then the code — together they are the 101 in one sitting.
02 — PICTURE clauses
Data is described by picture: seven digits, implied decimal point — layouts as types.
01 WAGE PIC 9(7)V99.
01 EMPLOYEE PIC X(20).03 — the verbs
Four hundred English words; a manager can almost read the payroll run.
MOVE WAGE TO OLD-WAGE.
ADD BONUS TO WAGE.
DISPLAY "NEW: " WAGE.201 — going deeper
The 201 assumes you have read the 101 and the specimen. Each lesson is one mechanism — what it is for, how it looks in code, and the trap or payoff that makes COBOL distinctive at scale.
copybooks and the linkage section
Record layouts live in copybooks shared across programs, and the linkage section passes them between units — an interface discipline that predates most languages.
*> crew.cpy
01 CREW-RECORD.
05 CREW-ID PIC 9(6).
05 CREW-NAME PIC X(20).tables and OCCURS
Fixed and variable-length tables, indexed like arrays, with OCCURS DEPENDING ON sizing the table to the record count.
01 PORT-CALLS OCCURS 50 TIMES
DEPENDING ON CREW-COUNT.
05 PORT-NAME PIC X(10).intrinsics and string handling
INSPECT, UNSTRING and STRING provide the text surgery that made COBOL the language of reports — heavy machinery for light work.
INSPECT CREW-NAME TALLYING ALPHA FOR CHARACTERS
BEFORE INITIAL "A" AFTER INITIAL "Z".
UNSTRING CREW-NAME DELIMITED BY SPACE INTO FIRST-NAME REST.The specimen — factorial
Data first: the record — named fields, pictures of their format — so a payroll program could read like the payroll office talks. Verbs for managers, structure for the machine.
MOVE WAGE TO OLD-WAGE.
ADD BONUS TO WAGE.
DISPLAY "NEW WAGE IS" WAGE.Run it today
installbrew install gnucobol
runcobc -x fact.cob && ./fact
Where it is now
Banks, insurers and governments settle your money through COBOL every single day; the retirement projects have all failed so far.