Memory model preview

Before diving into pointers, understand the two main memory regions C programs use: the stack and the heap.

Stack (automatic storage)

Local variables inside a function live on the stack. They are created when the function is called and destroyed when it returns—no free needed.

void greet(void) {
    int count = 1;   /* stack: gone when greet returns */
}

Heap (dynamic storage)

malloc requests memory that stays alive until you call free. Use it when size or lifetime exceeds a single function call.

Addresses and pointers (preview)

Every object has an address. A pointer stores that address: int *p = &count;. Dereferencing *p reads or writes through the pointer.

Important interview questions and answers

1. Q: Stack vs heap?
   A: Stack is automatic and fast; heap is manual, flexible, and must be freed to avoid leaks.
2. Q: What is a dangling pointer?
   A: A pointer to memory that is no longer valid—often after free or returning a pointer to a local stack variable.

Self-check

1. Where do local non-static variables live?
2. What function releases heap memory?

Tip: Draw boxes and arrows on paper for stack vs heap—visualizing addresses makes pointer lessons in Rust and C much easier later.