🪴 TJ's Notes 1.0

Data Structures & Algorithm Lecture 15

2 min read

Continued from Data Structures & Algorithm Lecture 14

C++ Pointer and Node Management

Indirectional Operator (*)

In C++, the indirectional operator (*) is used to declare a pointer and to dereference a pointer.

Example:

int *x;
  • In this line of code, int *x; declares a pointer x that is expected to store the address of an integer variable.
  • The operator * indicates that x is a pointer to an integer.

Key Points:

  • The indirectional operator does not store the value directly; instead, it stores the address of the variable that will hold an integer value.
  • You can later use this pointer to access or modify the value of the integer stored at the memory address it points to by dereferencing it using *.

Creating a Node and Assigning It as the Start

In linked lists or other dynamic data structures, creating and assigning nodes dynamically is a crucial operation.

Example Code:

Node* createNode(int data) {
    Node *newNode = (Node*)malloc(sizeof(Node));
    newNode->data = data;
    newNode->next = NULL;
    return newNode;
}

Explanation:

  • Node* createNode(int data): This function creates a new node that will store the given integer data.
  • malloc(sizeof(Node)): Allocates the necessary memory space for the node.
  • newNode->data = data: Assigns the data value to the node.
  • newNode->next = NULL: Initializes the pointer to the next node as NULL, meaning it is the last node in the list for now.

Steps Involved:

  1. Memory Allocation: Using malloc to allocate memory for a new node.
  2. Assigning Data: The data field in the node is assigned the value passed to the function.
  3. Next Pointer: The next pointer is initialized to NULL, meaning it doesn’t point to any other node yet.
  4. Return: Returns the pointer to the newly created node.

Malloc (malloc)

In C/C++, malloc is a function used to dynamically allocate memory at runtime.

Important Notes:

  • No Initial Memory Allocation: When malloc allocates memory, the allocated memory is not initialized; it may contain garbage values. You must explicitly assign values after allocation.

Example:

int *ptr = (int*)malloc(sizeof(int));

  • This allocates memory for one integer and returns a pointer to the memory location.

  • Syntax: malloc(size_in_bytes)

  • Returns: A pointer to the beginning of the allocated memory block or NULL if the allocation fails.

Note: After using malloc, it is important to free the allocated memory to avoid memory leaks.

Information

Graph View

Backlinks