The inputs I'm throwing at it are a common problem mistake in C programming which demonstrates a buffer overflow. K&R's code assumes that it will only be used in each program they've written, but it usually get copied out into other software and that causes the bugs. As I said, the programs are correct, the functions are not.

And no, most of the clever convoluted code in K&R is antiquated and the only reason it's a common C idiom is because nobody questions whether it's good style. It's more of a habit than an idiom.