Why am I getting segfault when changing the signature of main?

Question

I am trying to get my feet into C, and wrote this program that displays a kb of my RAM in a random location. Here is the code, and it works fine:

#include 

        

Answer 1

You never initialize mem, so its contents are undefined. When you attempt to either increment it with ++ or dereference the pointer, you get undefined behavior.

One of the things that can happen with undefined behavior is that a program may appear to work normally, and making a seemingly unrelated change will cause a crash.