Your First COBOL Program

With GnuCOBOL installed, you can write a complete, working COBOL program in under ten lines. Every runnable COBOL program needs, at minimum, an IDENTIFICATION DIVISION with a PROGRAM-ID, a PROCEDURE DIVISION with at least one statement, and a STOP RUN statement to terminate cleanly; the DATA DIVISION and ENVIRONMENT DIVISION are technically optional if the program neither declares variables nor touches files. The classic first program simply displays text to the console using the DISPLAY verb, which is COBOL's equivalent of print() in Python or System.out.println() in Java.

Save the program below as HELLO.cob (the .cob or .cbl extension is a convention GnuCOBOL recognizes, not strictly mandatory). Compile it with cobc -x -free -o hello HELLO.cob, where -x requests an executable, -free enables the beginner-friendly free-format source layout, and -o hello names the output binary. Running ./hello afterward executes the compiled program directly; on Windows via WSL or MinGW, the output binary would instead be hello.exe.

The most frequent early errors are: forgetting the trailing period after PROGRAM-ID or after a statement, which merges statements together in confusing ways; misplacing code in fixed-format Area A versus Area B when not using the -free flag; and forgetting STOP RUN, which in some environments causes the program to fall through into whatever paragraph happens to follow rather than terminating cleanly. Another very common mistake for beginners coming from other languages is expecting case sensitivity; COBOL keywords and most identifiers are traditionally case-insensitive, so DISPLAY, display, and Display are all treated identically by the compiler.