CobolD

COBOL → Python. Byte-perfect.

Found 6 bugs in this savings calculator. Three were silently eating money — off by hundreds of dollars on long-term deposits. Fixed directly in COBOL.

Also translating COBOL programs to Python so both produce identical output, byte for byte.

Verify

# Bug fix — 3 test cases, original vs fixed
cobc -x savings_verify.cob && ./savings_verify

# Translations
cobc -x mortgage.cob && ./mortgage > cobol.txt
python3 mortgage.py > python.txt
diff cobol.txt python.txt   # empty = byte-perfect

cobc -x unstring.cob && ./unstring-example > cobol.txt
python3 unstring.py > python.txt
diff cobol.txt python.txt

Files

File	Description
savings_original.cob	Original code with bugs
savings_fixed.cob	Fixed version, 6 bugs documented in header
savings_verify.cob	Side-by-side verification (3 test cases)
mortgage.cob / .py	30-year mortgage amortization
unstring.cob / .py	COBOL UNSTRING — 6 examples, full state machine

Requirements

• GnuCOBOL 3.x (brew install gnucobol / apt install gnucobol)
• Python 3.8+