[VonTum]

The article specifically mentions this optimization as not working with the compiler at that time, hence the need for the separate index variable.

> We will edit su.c to prevent the overflow by maintaining a counter, i, and verifying it against the buffer size during the read loop. I initially attempted a fix using pointer arithmetic, but the 1973 C compiler didn’t like it, while it didn’t refuse the syntax, the code had no effect. I settled on a simpler index-based check instead.

[asveikau]

Your sibling comment mentions it.

There's no details.. why didn't it work? Maybe the author didn't write it correctly? No word on what the assembly output for it was...