🚀 Programming Example
C Program of dequeue using a circular array
C Program of deque using a circular array
/* C Program of dequeue using a circular array*/
#include<stdio.h>
#include<stdlib.h>
#define MAX 7
int deque_arr[MAX];
int front=-1;
int rear=-1;
void insert_frontEnd(int item);
void insert_rearEnd(int item);
int delete_frontEnd();
int delete_rearEnd();
void display();
int isEmpty();
int isFull();
main()
{
int choice,item;
while(1)
{
printf("1.Insert at the front end\n");
printf("2.Insert at the rear end\n");
printf("3.Delete from front end\n");
printf("4.Delete from rear end\n");
printf("5.Display\n");
printf("6.Quit\n");
printf("Enter your choice : ");
scanf("%d",&choice);
switch(choice)
{
case 1:
printf("Input the element for adding in queue : ");
scanf("%d",&item);
insert_frontEnd(item);
break;
case 2:
printf("Input the element for adding in queue : ");
scanf("%d",&item);
insert_rearEnd(item);
break;
case 3:
printf("Element deleted from front end is : %d\n",delete_frontEnd());
break;
case 4:
printf("Element deleted from rear end is : %d\n",delete_rearEnd());
break;
case 5:
display();
break;
case 6:
exit(1);
default:
printf("Wrong choice\n");
}/*End of switch*/
printf("front = %d, rear =%d\n", front , rear);
display();
}/*End of while*/
}/*End of main()*/
void insert_frontEnd(int item)
{
if( isFull() )
{
printf("Queue Overflow\n");
return;
}
if( front==-1 )/*If queue is initially empty*/
{
front=0;
rear=0;
}
else if(front==0)
front=MAX-1;
else
front=front-1;
deque_arr[front]=item ;
}/*End of insert_frontEnd()*/
void insert_rearEnd(int item)
{
if( isFull() )
{
printf("Queue Overflow\n");
return;
}
if(front==-1) /*if queue is initially empty*/
{
front=0;
rear=0;
}
else if(rear==MAX-1) /*rear is at last position of queue */
rear=0;
else
rear=rear+1;
deque_arr[rear]=item ;
}/*End of insert_rearEnd()*/
int delete_frontEnd()
{
int item;
if( isEmpty() )
{
printf("Queue Underflow\n");
exit(1);
}
item=deque_arr[front];
if(front==rear) /*Queue has only one element */
{
front=-1;
rear=-1;
}
else
if(front==MAX-1)
front=0;
else
front=front+1;
return item;
}/*End of delete_frontEnd()*/
int delete_rearEnd()
{
int item;
if( isEmpty() )
{
printf("Queue Underflow\n");
exit(1);
}
item=deque_arr[rear];
if(front==rear) /*queue has only one element*/
{
front=-1;
rear=-1;
}
else if(rear==0)
rear=MAX-1;
else
rear=rear-1;
return item;
}/*End of delete_rearEnd() */
int isFull()
{
if ( (front==0 && rear==MAX-1) || (front==rear+1) )
return 1;
else
return 0;
}/*End of isFull()*/
int isEmpty()
{
if( front == -1)
return 1;
else
return 0;
}/*End of isEmpty()*/
void display()
{
int i;
if( isEmpty() )
{
printf("Queue is empty\n");
return;
}
printf("Queue elements :\n");
i=front;
if( front<=rear )
{
while(i<=rear)
printf("%d ",deque_arr[i++]);
}
else
{
while(i<=MAX-1)
printf("%d ",deque_arr[i++]);
i=0;
while(i<=rear)
printf("%d ",deque_arr[i++]);
}
printf("\n");
}/*End of display() */
1.Insert at the front end
2.Insert at the rear end
3.Delete from front end
4.Delete from rear end
5.Display
6.Quit
Enter your choice : 1
Input the element for adding in queue : 12
front = 0, rear =0
Queue elements :
12
1.Insert at the front end
2.Insert at the rear end
3.Delete from front end
4.Delete from rear end
5.Display
6.Quit
Enter your choice : 2
Input the element for adding in queue : 14
front = 0, rear =1
Queue elements :
12 14
1.Insert at the front end
2.Insert at the rear end
3.Delete from front end
4.Delete from rear end
5.Display
6.Quit
Enter your choice : 3
Element deleted from front end is : 12
front = 1, rear =1
Queue elements :
14
1.Insert at the front end
2.Insert at the rear end
3.Delete from front end
4.Delete from rear end
5.Display
6.Quit
Enter your choice : 45
Wrong choice
front = 1, rear =1
Queue elements :
14
1.Insert at the front end
2.Insert at the rear end
3.Delete from front end
4.Delete from rear end
5.Displa
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.