Certainly I have (the former, not the latter). You won't be surprised when I tell you that it wasn't a horrible tragedy and that I didn't die on the spot because of this, or accidentally purchase a handgun instead of a watermelon. In fact, it was such a minor event that I hadn't taken the time to make plans ahead of time for such an eventuality. Likewise, the first time I used pointers, nobody told me ahead of time that it was even possible to have a pointer that pointed to nothing. Understanding this, and (more crucially) learning exactly how to know when a pointer was and was not valid, was what got me my first merit badge in C. Everything before that was just Pascal with less formality.