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Pointers & memory model
Section 1 of 4
Before diving into linked lists, we need to understand pointers - the building blocks that make dynamic data structures possible. Master these fundamentals first!
Linked lists are built entirely on pointer relationships. Without understanding how pointers work, memory addresses, and dynamic allocation, linked list operations will seem like magic. Let's demystify it!
Every variable has a location in memory - this location has an address
int x = 42; int *ptr = &x; // ptr stores address of x
Variable x stored at memory address 1000
Foundation of dynamic data structures
Using * operator to access the value stored at the memory address
int value = *ptr; // Gets value 42 *ptr = 100; // Changes x to 100
Access the actual data through the pointer
Read/write data through pointers
Special pointer value indicating no valid memory location
Node *head = NULL;
if (head != NULL) {
// Safe to use
}Points to "nothing" - marks end of list
Marks list boundaries and prevents crashes
Allocating memory during program execution (runtime)
Node *newNode = malloc(sizeof(Node)); // or in C++: Node *newNode = new Node();
Create memory space when needed
Enables flexible runtime-sized structures
Think of computer memory like a huge apartment building. Each apartment has a unique address (like 0x1000), and can store data. Pointers are like sticky notes that have the address written on them!
// Step 1: Create variable
int x = 42;
printf("x = %d", x);Now you understand the foundation! In linked lists, each node will be a dynamically allocated piece of memory, connected to the next through pointers.
struct Node {
int data; // The value
Node* next; // Pointer to next node
};