Is queue a singly linked list?
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The major problem with the queue implemented using an array is, It will work for an only fixed number of data values. That means, the amount of data must be specified at the beginning itself. Queue using an array is not suitable when we don't know the size of data which we are going to use. A queue data structure can be implemented using a linked list data structure. The queue which is implemented using a linked list can work for an unlimited number of values. That means, queue using linked list can work for the variable size of data (No need to fix the size at the beginning of the implementation). The Queue implemented using linked list can organize as many data values as we want. In linked list implementation of a queue, the last inserted node is always pointed by 'rear' and the first node is always pointed by 'front'. In above example, the last inserted node is 50 and it is pointed by 'rear' and the first inserted node is 10 and it is pointed by 'front'. The order of elements inserted is 10, 15, 22 and 50. To implement queue using linked list, we need to set the following things before implementing actual operations.
We can use the following steps to insert a new node into the queue...
We can use the following steps to delete a node from the queue...
We can use the following steps to display the elements (nodes) of a queue...
#include
#include
struct Node
{
int data;
struct Node *next;
}*front = NULL,*rear = NULL;
void insert(int);
void delete();
void display();
void main()
{
int choice, value;
clrscr();
printf("\n:: Queue Implementation using Linked List ::\n");
while(1){
printf("\n****** MENU ******\n");
printf("1. Insert\n2. Delete\n3. Display\n4. Exit\n");
printf("Enter your choice: ");
scanf("%d",&choice);
switch(choice){
case 1: printf("Enter the value to be insert: ");
scanf("%d", &value);
insert(value);
break;
case 2: delete(); break;
case 3: display(); break;
case 4: exit(0);
default: printf("\nWrong selection!!! Please try again!!!\n");
}
}
}
void insert(int value)
{
struct Node *newNode;
newNode = (struct Node*)malloc(sizeof(struct Node));
newNode->data = value;
newNode -> next = NULL;
if(front == NULL)
front = rear = newNode;
else{
rear -> next = newNode;
rear = newNode;
}
printf("\nInsertion is Success!!!\n");
}
void delete()
{
if(front == NULL)
printf("\nQueue is Empty!!!\n");
else{
struct Node *temp = front;
front = front -> next;
printf("\nDeleted element: %d\n", temp->data);
free(temp);
}
}
void display()
{
if(front == NULL)
printf("\nQueue is Empty!!!\n");
else{
struct Node *temp = front;
while(temp->next != NULL){
printf("%d--->",temp->data);
temp = temp -> next;
}
printf("%d--->NULL\n",temp->data);
}
}
Output |
