C program to Implement Singly Linked List

Singly Linked List

Singly linked lists contain nodes which have a data part as well as an address part i.e. next, which points to the next node in sequence of nodes. The operations we can perform on singly linked lists are insertion, deletion and traversal.

Here is source code of the C Program to Implement Singly Linked List using Dynamic Memory Allocation. The C program is successfully compiled and run on a Linux system. The program output is also shown below.

#include<stdio.h>

struct linked_list_node{
    int num;
    struct linked_list_node *next;
};

typedef struct linked_list_node snode;

snode *first = NULL;
snode *last = NULL;

void insertNode(int value);
void insertAtFirst(int value);
void deleteFirst();
void deleteLast();
snode *createNode(int value);
void display();

void main()
{
    int choice, nValue;
    char ch='y';

    while (ch == 'y')
    {
        printf("\n------------------------------\n");
        printf("\tSingly Linked List\n");
        printf("------------------------------\n");

        printf("\n1. Insert a node at last\n");
        printf("2. Insert a node at first\n");
        printf("3. Delete First Node\n");
        printf("4. Delete Last Node\n");
        printf("5.Display contents of list\n");
        printf("Enter your choice: ");
        scanf("%d", &choice);

        switch(choice)
        {
            case 1:
                    printf("\nInserting a new node at last.....\n");
                    printf("Enter the value of node: ");
                    scanf("%d", &nValue);
                    insertNode(nValue);
                    break;
            case 2:
                    printf("\nInserting a node at first.....\n");
                    printf("Enter the value of node: ");
                    scanf("%d", &nValue);
                    insertAtFirst(nValue);
                    break;
            case 3:
                    printf("\nDeleteing first node.....\n");
                    deleteFirst();
                    break;
            case 4:
                    printf("\nDeleteing last node.....\n");
                    deleteLast();
                    break;
            case 5:
                    printf("\nContents of linked list are as follows\n");
                    display();
                    break;
            default:
                    printf("\nInvalid choice!!!\n");
        }

        printf("\nDo you want to continue(y/n)?" );
        scanf(" %c", &ch);
    }
}

snode *createNode(int value)
{
    snode *newNode;

    newNode = (snode *)malloc(sizeof(snode));
    newNode->num = value;
    newNode->next = NULL;
    return newNode;
}

void insertNode(int value)
{
    snode *newNode;
    newNode = createNode(value);

    if (first == last && first == NULL)
    {
        first = last = newNode;
    }
    else
    {
        last->next = newNode;
        last = newNode;
    }
}

void insertAtFirst(int value)
{
    snode *newNode;
    newNode = createNode(value);

    newNode->next = first;
    first = newNode;
}

void deleteFirst()
{
    if (first == NULL)
    {
        printf("List is empty!!!\n");
    }
    else if (first == last)
    {
        first = last = NULL;
        printf("Node successfully deleted!!!\n");
    }
    else
    {
        first = first->next;
        printf("Node successfully deleted!!!\n");
    }
}

void deleteLast()
{
    snode *temp;
    if (first == NULL)
    {
        printf("List is empty!!!\n");
    }
    else if (first == last)
    {
        first = last = NULL;
        printf("Node successfully deleted!!!\n");
    }
    else
    {
        temp = first;
        while (temp)
        {
            if (temp->next == last)
            {
                break;
            }
            temp = temp->next;
        }
        last = temp;
        printf("Node successfully deleted!!!\n");
    }
}

void display()
{
    snode *temp = first;

    if (first == NULL)
    {
        printf("List is empty!!!\n");
        return;
    }

    while (temp != last)
    {
        printf("%d-->", temp->num);
        temp = temp->next;
    }
    printf("%d", last->num);
}

Output:

----------------------------------------------
    Singly Linked List
----------------------------------------------

1. Insert a node at last
2. Insert a node at first
3. Delete First Node
4. Delete Last Node
5.Display contents of list

Enter your choice: 1

Inserting a new node at last.....
Enter the value of node: 5

Do you want to continue(y/n)?y

--------------------------------------------
    Singly Linked List
-------------------------------------------

1. Insert a node at last
2. Insert a node at first
3. Delete First Node
4. Delete Last Node
5.Display contents of list

Enter your choice: 1

Inserting a new node at last.....
Enter the value of node: 6

Do you want to continue(y/n)?y

-------------------------------------------
    Singly Linked List
-------------------------------------------

1. Insert a node at last
2. Insert a node at first
3. Delete First Node
4. Delete Last Node
5.Display contents of list

Enter your choice: 5

Contents of linked list are as follows
5-->6

Do you want to continue(y/n)?y

-----------------------------------------
    Singly Linked List
-----------------------------------------

1. Insert a node at last
2. Insert a node at first
3. Delete First Node
4. Delete Last Node
5.Display contents of list

Enter your choice: 2

Inserting a node at first.....
Enter the value of node: 4

Do you want to continue(y/n)?y

------------------------------------------
    Singly Linked List
------------------------------------------

1. Insert a node at last
2. Insert a node at first
3. Delete First Node
4. Delete Last Node
5.Display contents of list

Enter your choice: 5

Contents of linked list are as follows
4-->5-->6

Do you want to continue(y/n)?y

-----------------------------------------
    Singly Linked List
-----------------------------------------

1. Insert a node at last
2. Insert a node at first
3. Delete First Node
4. Delete Last Node
5.Display contents of list

Enter your choice: 3

Deleting first node.....
Node successfully deleted!!!

Do you want to continue(y/n)?y

-----------------------------------------
    Singly Linked List
-----------------------------------------

1. Insert a node at last
2. Insert a node at first
3. Delete First Node
4. Delete Last Node
5.Display contents of list

Enter your choice: 5

Contents of linked list are as follows
5-->6

Do you want to continue(y/n)?y

-------------------------------------------
    Singly Linked List
-------------------------------------------

1. Insert a node at last
2. Insert a node at first
3. Delete First Node
4. Delete Last Node
5.Display contents of list

Enter your choice: 4

Deleteing last node.....
Node successfully deleted!!!

Do you want to continue(y/n)?y

-------------------------------------------
    Singly Linked List
-------------------------------------------

1. Insert a node at last
2. Insert a node at first
3. Delete First Node
4. Delete Last Node
5.Display contents of list

Enter your choice: 5

Contents of linked list are as follows
5

Do you want to continue(y/n)?

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