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c code for queue using linked list.

July ,7th ,2022
cqueue using linked list
write a c code for queue using linked list.

Write a menu-driven program to implement queue operations such as Enqueue, Dequeue, Peek, Display of elements, and Is Empty using a linked list.

Code

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

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

struct Node *f = NULL;
struct Node *r = NULL;

int isFull()
{
    struct Node *n = (struct Node *)malloc(sizeof(struct Node));
    if (n == NULL)
    {
        return 1;
    }
    return 0;
}

int isEmpty()
{
    if (f == NULL)
    {
        return 1;
    }
    return 0;
}

void linkedListTraversal(struct Node *ptr)
{
    printf("Printing the elements of this linked list\n");
    while (ptr != NULL)
    {
        printf("Element: %d\n", ptr->data);
        ptr = ptr->next;
    }
}

void enqueue(int val)
{
    struct Node *n = (struct Node *)malloc(sizeof(struct Node));
    if (isFull())
    {
        printf("Queue is Full");
    }
    else
    {
        n->data = val;
        n->next = NULL;
        if (f == NULL)
        {
            f = r = n;
        }
        else
        {
            r->next = n;
            r = n;
        }
    }
}

int dequeue()
{
    int val = -1;
    struct Node *ptr = f;
    if (f == NULL)
    {
        printf("Queue is Empty\n");
    }
    else
    {
        f = f->next;
        val = ptr->data;
        free(ptr);
    }
    return val;
}

int main()
{
    int c, i;
    while (1)
    {
        options:
        printf("\n1.enqueue\n");
        printf("2.dequeue\n");
        printf("3.Display element at the front\n");
        printf("4.Display element at the rear\n");
        printf("5.Display all elements of the queue\n");
        printf("6.isFull\n");
        printf("7.isEmpty\n");
        printf("8.Quit\n");
        printf("\nEnter your choice : ");
        scanf("%d", &c);

        switch (c)
        {
        case 1:
            printf("\nInput the element for adding in queue : ");
            scanf("%d", &i);
            enqueue(i);
            break;
        case 2:
            i = dequeue();
            printf("\nDeleted element is  %d\n", i);
            break;
        case 3:
            printf("\nElement at the front is %d\n", f->data);
            break;
        case 4:
            printf("\nElement at the rear is %d\n", r->data);
            break;
        case 5:
            linkedListTraversal(f);
            break;
        case 6:
            if (isFull())
            {
                printf("Queue is full\n");
            }
            else
            {
                printf("Queue is not full\n");
            }
            break;
        case 7:
            if (isEmpty())
            {
                printf("Queue is empty\n");
            }
            else
            {
                printf("Queue is not empty\n");
            }
            break;
        case 8:
            exit(1);
        default:
            printf("\nWrong choice\n");
        }
    }
    return 0;
}