linearqueuelinkedlist.c

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

struct node { 
    int data; 
    struct node *next; 
};
struct node *front = NULL, *rear = NULL;

void enqueue(int x) {
    struct node *newnode = (struct node *)malloc(sizeof(struct node));
    newnode->data = x; 
    newnode->next = NULL;
    if (front == NULL && rear == NULL) { 
        front = rear = newnode; 
    } else { 
        rear->next = newnode; 
        rear = newnode; 
    }
}

void dequeue() {
    if (front == NULL && rear == NULL) { 
        printf("Underflow\n"); 
        return; 
    }
    struct node *temp = front;
    printf("Deleted: %d\n", front->data);
    if (front == rear) { 
        front = rear = NULL; 
    } else { 
        front = front->next; 
    }
    free(temp);
}

void display() {
    if (front == NULL) { 
        printf("Queue is empty\n"); 
        return; 
    }
    struct node *temp = front;
    printf("Queue: ");
    while (temp != NULL) { 
        printf("%d ", temp->data); 
        temp = temp->next; 
    }
    printf("\n");
}

int main() {
    enqueue(15); enqueue(10); enqueue(30);
    display(); 
    dequeue(); 
    display();
    return 0;
}