Heap vs. stack

How can you tell how far in bytes something is located from the heap or stack? Wouldn't it depend on what you've limited your stack size to? I know the heap and stack are on "opposite sides of each other" (or so my prof drew it out like so), but when I used the "operator of" to figure out where in memory my variables sit they seem to be one right after the other. So i'm just a bit confused about this.

I appreciate the feedback. :]