Printf-Tac-Toe

Contestant: "I'll take My Dirty Programming Secrets for 100, Alex."

Alex: "Its primary purpose is to serve as The One True Debugger."

(It has certainly served me well.)

That's the content why I check HN! :)

To be fair, this is actually `scanf` and `printf` in a loop. The `scanf` is buried in the `arg` define.

This is both impressive and slightly terrifying. Format strings are way more powerful than most people realize.

How did we end up with printf - within a loop - being Turing-complete? Was it designed that way from the beginning? Were new features added over time until we got there?