C Singly Linked List 🎯

Welcome to our deep dive into C Singly Linked Lists! In this lesson, we'll explore what a Singly Linked List is, why we use them, and how to create and manipulate them in C. Let's get started!

Understanding Singly Linked Lists 📝

A Singly Linked List is a linear data structure made up of nodes where each node contains data and a reference to the next node in the list. Each node in a Singly Linked List only points to the next node, not the previous one.

Diagram of a Singly Linked List

💡 Pro Tip:

Singly Linked Lists are useful when we don't know the size of the data beforehand, making them dynamic and adaptable.

Creating a Singly Linked List Node ✅

To create a Singly Linked List in C, we first need to define a structure for a Node, which will contain data and a pointer to the next Node.

struct Node {
    int data;
    struct Node* next;
};

Here, struct Node is a user-defined data type. Inside this structure, data stores the value of the current node, and next is a pointer to the next node in the list.

Creating a Linked List ✅

Now that we have the Node structure, let's create a Singly Linked List. We'll start by initializing the head of the list as NULL, indicating an empty list.

struct Node* head = NULL;

To add nodes to the list, we'll create a function called insertNode(). This function will create a new Node, set its data to the provided value, and make it the head of the list or append it to the end of the existing list.

void insertNode(int data) {
    struct Node* newNode = (struct Node*) malloc(sizeof(struct Node));
    newNode->data = data;
    newNode->next = NULL;

    if (head == NULL) {
        head = newNode;
    } else {
        struct Node* current = head;
        while (current->next != NULL) {
            current = current->next;
        }
        current->next = newNode;
    }
}

💡 Pro Tip:

Always use malloc() to dynamically allocate memory for new nodes.

Deleting a Node ✅

Removing a node from a Singly Linked List involves finding the node to be deleted and changing the pointer of the previous node to skip the removed node. We'll create a function called deleteNode() for this purpose.

void deleteNode(int key) {
    if (head == NULL) {
        printf("List is empty.\n");
        return;
    }

    if (head->data == key) {
        struct Node* temp = head;
        head = head->next;
        free(temp);
        return;
    }

    struct Node* current = head;
    while (current->next != NULL && current->next->data != key) {
        current = current->next;
    }

    if (current->next == NULL) {
        printf("Element not found.\n");
        return;
    }

    struct Node* temp = current->next;
    current->next = current->next->next;
    free(temp);
}

💡 Pro Tip:

Make sure to handle the case where the list is empty and the case where the node to be deleted is the head of the list.

Quiz Time! 🎯

Now that you have a grasp of Singly Linked Lists, practice by implementing the complete implementation of inserting, deleting, and displaying nodes in a Singly Linked List. Good luck, and happy coding! 🚀