Not putting a format specifier wouldn't cause a segfault.

Well, there is a difference between "format specifier" and "format string". The first argument to printf is the format string, the `%d` and `%s` type things are the format specifiers. I was talking about this

    printf("Hi", 45);

which will not segfault. If you meant

    printf(45);

Then you are absolutely correct, that would segfault on common machines.

I think that must be it. And it makes perfect sense how he would hit it. Example: http://ideone.com/MilaUN

Deleted my comment because you are, of course, correct. (However, I do suspect rayiner was referring to omitting the format string.)

I think so too, I just have bad reading comprehension and should have known but didn't.