A Punch Card ate my Program!

on YouTube ↗11m

" summary

Recreates a production bug: a stray period in column 73 terminates a COBOL sentence unexpectedly because COBOL uses COBOL sentence termination (periods end sentences) and old punch‑card layouts enforce a punch card column 72 limit so characters after column 72 are ignored. Uses syntax highlighting and compiler options (free format vs fixed) to diagnose the mismatch between two systems, then shifts the period one column and the program prints correct shipping and free‑ship logic.

AI-written summary · about

" chapters (5)

1. 0:00Introduction to COBOL
2. 1:43The mysterious bug
3. 3:18Syntax and design history
4. 5:05The role of the period
5. 7:27Punch cards and the fix

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