Program for Implementation of a Queue Using Linked Representation with Example

Program

A complete C program for implementation of a stack using the linked list is shown here:

# include <stdio.h>
# include <stdlib.h>
struct node
{
   int data;
   struct node *link;
};

void insert(struct node **front, struct node **rear, int value)
{
   struct node *temp;
   temp=(struct node *)malloc(sizeof(struct node));
       /* creates new node
       using data value
       passed as parameter */
   if(temp==NULL)
   {
      printf("No Memory available Error\n");
      exit(0);
   }
   temp->data = value;
   temp->link=NULL;
   if(*rear == NULL)
   {
      *rear = temp;
      *front = *rear;
   }
   else
   {
      (*rear)->link = temp;
      *rear = temp;
   }
}

void delete(struct node **front, struct node **rear, int *value)
{
   struct node *temp;
   if((*front == *rear) && (*rear == NULL))
   {
      printf(" The queue is empty cannot delete Error\n");
      exit(0);
   }
   *value = (*front)->data;
   temp = *front;
   *front = (*front)->link;
   if(*rear == temp)
   *rear = (*rear)->link;
   free(temp);
}

void main()
{
   struct node *front=NULL,*rear = NULL;
   int n,value;
   do
   {
      do
      {
            printf("Enter the element to be inserted\n");
         scanf("%d",&value);
         insert(&front,&rear,value);
         printf("Enter 1 to continue\n");
         scanf("%d",&n);
      } while(n == 1);

      printf("Enter 1 to delete an element\n");
      scanf("%d",&n);
      while( n == 1)
      {
            delete(&front,&rear,&value);
            printf("The value deleted is %d\n",value);
            printf("Enter 1 to delete an element\n");
            scanf("%d",&n);
      }
      printf("Enter 1 to continue\n");
      scanf("%d",&n);
   } while(n == 1);
}

Example

Input and Output

Enter the element to be inserted

10

Enter 1 to continue

1

Enter the element to be inserted

20

Enter 1 to continue

1

Enter the element to be inserted

30

Enter 1 to continue

0

Enter 1 to delete an element

1

The value deleted is 10
Enter 1 to delete an element

1

The value deleted is 20
Enter 1 to delete an element

0

Enter 1 to continue

1

Enter the element to be inserted

40

Enter 1 to continue

1

Enter the element to be inserted

50

Enter 1 to continue

0

Enter 1 to delete an element

1

The value deleted is 30
Enter 1 to pop an element

1

The value deleted is 40
Enter 1 to delete an element

1

The value deleted is 50

Enter 1 to delete an element

1

The queue is empty, cannot delete Error