This probably needs some context ... C at the time was still developing, lots of stuff was optional, parameters were int if you didn't define their type. V6 uni

This probably needs some context ... C at the time was still developing, lots of stuff was optional, parameters were int if you didn't define their type. V6 unix was a decade old and already wouldn't compile on K&R compilers, struct became genuinely unique types (requiring the creation of union, because struct could no longer be tweaked to do the same thing). This was written at the end of that period where most people had an understanding of 'how it should be', while others were still using some of the older idiom ....