//C program to delete first node from Singly Linked List
 

#include <stdio.h>
#include <stdlib.h>

/* Structure of a node */
struct node
{
    int data;          // Data
    struct node *next; // Address
} *head;

/*
 * Create a list of n nodes
 */
void createList(int n)
{
    struct node *newNode, *temp;
    int data, i;

    head = (struct node *)malloc(sizeof(struct node));

    /*
     * If unable to allocate memory for head node
     */
    if (head == NULL)
    {
        printf("Unable to allocate memory.");
    }
    else
    {
        /*
         * In data of node from the user
         */
        printf("Enter the data of node 1: ");
        scanf("%d", &data);

        head->data = data; // Link the data field with data
        head->next = NULL; // Link the address field to NULL

        temp = head;

        /*
         * Create n nodes and adds to linked list
         */
        for (i = 2; i <= n; i++)
        {
            newNode = (struct node *)malloc(sizeof(struct node));

            /* If memory is not allocated for newNode */
            if (newNode == NULL)
            {
                printf("Unable to allocate memory.");
                break;
            }
            else
            {
                printf("Enter the data of node %d: ", i);
                scanf("%d", &data);

                newNode->data = data; // Link the data field of newNode with data
                newNode->next = NULL; // Link the address field of newNode with NULL

                temp->next = newNode; // Link previous node i.e. temp to the newNode
                temp = temp->next;
            }
        }

        printf("SINGLY LINKED LIST CREATED SUCCESSFULLY\n");
    }
}

/*
 * Deletes the first node of the linked list
 */
void deleteFirstNode()
{
    struct node *toDelete;

    if (head == NULL)
    {
        printf("List is already empty.");
    }
    else
    {
        toDelete = head;
        head = head->next;

        printf("\nData deleted = %d\n", toDelete->data);

        /* Clears the memory occupied by first node*/
        free(toDelete);

        printf("SUCCESSFULLY DELETED FIRST NODE FROM LIST\n");
    }
}

/*
 * Displays the entire list
 */
void displayList()
{
    struct node *temp;

    /*
     * If the list is empty i.e. head = NULL
     */
    if (head == NULL)
    {
        printf("List is empty.");
    }
    else
    {
        temp = head;
        while (temp != NULL)
        {
            printf(" %d ", temp->data); // Print data of current node
            temp = temp->next;                 // Move to next node
        }
    }
}

int main()
{
    int n, choice;

    /*
     * Create a singly linked list of n nodes
     */
    printf("Enter the total number of nodes: ");
    scanf("%d", &n);
    createList(n);

    printf("\nData in the list \n");
    displayList();

    printf("\nPress 1 to delete first node: ");
    scanf("%d", &choice);

    /* Delete first node from list */
    if (choice == 1)
        deleteFirstNode();

    printf("\nData in the list \n");
    displayList();

    return 0;
}

Output

Enter the total number of nodes: 5
Enter the data of node 1: 10
Enter the data of node 2: 20
Enter the data of node 3: 30
Enter the data of node 4: 40
Enter the data of node 5: 50
SINGLY LINKED LIST CREATED SUCCESSFULLY

Data in the list
 10  20  30  40  50
Press 1 to delete first node: 1

Data in the list
20  30  40  50