🚀 Programming Example
C Program of the queue using the circular linked list
C Program of the queue using the circular linked list
/* Program of the queue using circular linked list*/
#include<stdio.h>
#include<stdlib.h>
struct node
{
int info;
struct node *link;
}*rear=NULL;
void insert(int item);
int del();
void display();
int isEmpty();
int peek();
main()
{
int choice,item;
while(1)
{
printf("1.Insert\n");
printf("2.Delete\n");
printf("3.Peek\n");
printf("4.Display\n");
printf("5.Quit\n");
printf("Enter your choice : ");
scanf("%d",&choice);
switch(choice)
{
case 1:
printf("Enter the element for insertion : ");
scanf("%d",&item);
insert(item);
break;
case 2:
printf("Deleted element is %d\n",del());
break;
case 3:
printf("Item at the front of queue is %d\n",peek());
break;
case 4:
display();
break;
case 5:
exit(1);
default:
printf("Wrong choice\n");
}/*End of switch*/
}/*End of while*/
}/*End of main()*/
void insert(int item)
{
struct node *tmp;
tmp=(struct node *)malloc(sizeof(struct node));
tmp->info=item;
if(tmp==NULL)
{
printf("Memory not available\n");
return;
}
if( isEmpty() ) /*If queue is empty */
{
rear=tmp;
tmp->link=rear;
}
else
{
tmp->link=rear->link;
rear->link=tmp;
rear=tmp;
}
}/*End of insert()*/
del()
{
int item;
struct node *tmp;
if( isEmpty() )
{
printf("Queue underflow\n");
exit(1);
}
if(rear->link==rear) /*If only one element*/
{
tmp=rear;
rear=NULL;
}
else
{
tmp=rear->link;
rear->link=rear->link->link;
}
item=tmp->info;
free(tmp);
return item;
}/*End of del()*/
int peek()
{
if( isEmpty() )
{
printf("Queue underflow\n");
exit(1);
}
return rear->link->info;
}/* End of peek() */
int isEmpty()
{
if( rear == NULL )
return 1;
else
return 0;
}/*End of isEmpty()*/
void display()
{
struct node *p;
if(isEmpty())
{
printf("Queue is empty\n");
return;
}
printf("Queue is :\n");
p=rear->link;
do
{
printf("%d ",p->info);
p=p->link;
}while(p!=rear->link);
printf("\n");
}/*End of display()*/
1.Insert
2.Delete
3.Peek
4.Display
5.Quit
Enter your choice : 1
Enter the element for insertion : 12
1.Insert
2.Delete
3.Peek
4.Display
5.Quit
Enter your choice : 3
Item at the front of queue is 12
1.Insert
2.Delete
3.Peek
4.Display
5.Quit
Enter your choice : 1
Enter the element for insertion : 15
1.Insert
2.Delete
3.Peek
4.Display
5.Quit
Enter your choice : 4
Queue is :
12 15
1.Insert
2.Delete
3.Peek
4.Display
5.Quit
Enter your choice : 2
Deleted element is 12
1.Insert
2.Delete
3.Peek
4.Display
5.Quit
Enter your choice : 4
Queue is :
15
1.Insert
2.Delete
3.Peek
4.Display
5.Quit
Enter your choice : 5
Press any key to continue . . .
First understand the algorithm carefully. Then study the program line-by-line and compare it with the output. Finally, review the explanation section to strengthen your logic and programming understanding.
Rewrite the program without looking at the code. Modify values, conditions or logic and run it again. This helps improve confidence and strengthens coding skills much faster.