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Circular_Queue.c
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Circular_Queue.c
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//IMPLEMENTING CIRCULAR QUEUE USING ARRAY
#include<stdio.h>
#include<conio.h>
//Declaring global variables
#define MAX 10
int queue[MAX];
int front=-1,rear=-1;
void enQueue(void);
int deQueue(void);
int peek(void);
int peekrear(void);
int avail(void);
void search(void);
void display(void);
int main()
{
int option,val;
printf("************CIRCULAR QUEUE*************");
printf("***************MAIN MENU***************");
printf("\n1.Insert an element.(ENQUEUE)");
printf("\n2.Delete an element.(DEQUEUE)");
printf("\n3.Peek front.");
printf("\n4.Peek rear.");
printf("\n5.Display the queue.");
printf("\n6.Spaces available.");
printf("\n7.Search.");
printf("\n8.EXIT");
top:
printf("\nYour option:\t");
scanf("%d",&option);
switch(option)
{
case 1:
enQueue();
break;
case 2:
val=deQueue();
if(val!=-1)
printf("\nElement deleted:\t%d",val);
break;
case 3:
val=peek();
if(val!=-1)
printf("\nElement in the front of the queue is:\t%d",val);
break;
case 4:
val=peekrear();
if(val!=-1)
printf("\nElement in the rear of the queue is:\t%d",val);
break;
case 5:
display();
break;
case 6:
val=avail();
printf("\n%d spaces are available.",val);
break;
case 7:
search();
break;
case 8:
exit(0);
break;
default:
printf("\nINVALID INPUT.");
break;
}
goto top;
return 0;
}
//-----------------------------------------------------------------------------------------
//INSERT OR ENQUEUE
void enQueue(void)
{
int val;
if((front==0 && rear==MAX-1)||(rear==front-1))
{
printf("\nQueue is full.");//OVERFLOW
}
else
{
printf("\nEnter an integer you wish to insert:\t");
scanf("%d",&val);
if(front==-1 && rear==-1)
{
front=rear=0;//EMPTY QUEUE
}
else if(rear==MAX-1 && front!=0)
{
rear=0;
}
else
{
rear=rear+1;
}
queue[rear]=val;
}
}
//DELETE OR DEQUEUE
int deQueue(void)
{
int val;
if(front==-1 && rear==-1) //EMPTY
{
printf("\nQueue is already empty.");
return -1;
}
else
{
val=queue[front];
if(front==MAX-1)
{
front=0;
}
else
{
front=front+1;
}
return val;
}
}
//PEEK
int peek(void)
{
int val;
if(front==-1 && rear==-1) //EMPTY
{
printf("\nQueue is empty.");
return -1;
}
else
{
val=queue[front];
return val;
}
}
//PEAKREAR
int peekrear(void)
{
int val;
if(front==-1 && rear==-1) //EMPTY
{
printf("\nQueue is empty.");
return -1;
}
else
{
val=queue[rear];
return val;
}
}
//AVAILABLE
int avail(void)
{
int val;
if(front<rear)
{
val=(MAX-1-rear)+(front);
}
else
{
val=rear-front-1;
}
return val;
}
//SEARCH
void search(void)
{
int num,i;
if(front==-1 && rear==-1) //EMPTY
{
printf("\nQueue is empty.");
}
else
{
printf("\nEnter the value you want to search.");
scanf("%d",&num);
if(front<rear)
{
for(i=front;i<=rear;i++)
{
if(queue[i]==num)
{
printf("\n%d is present at index %d and position %d",num,i,i+1);
}
}
}
else //rear<front
{
for(i=front;i<=MAX-1;i++)
{
if(queue[i]==num)
{
printf("\n%d is present at position %d",num,i);
}
}
for(i=0;i<=rear;i++)
{
if(queue[i]==num)
{
printf("\n%d is present at position %d",num,i);
}
}
}
}
}
//DISPLAY
void display(void)
{
int i;
if(front==-1 && rear==-1) //EMPTY
{
printf("\nQueue is empty.");
}
else if(front<rear)
{
for(i=front;i<=rear;i++)
{
printf("%d\t",queue[i]);
}
}
else //rear<front
{
for(i=front;i<=MAX-1;i++)
printf("%d\t",queue[i]);
for(i=0;i<=rear;i++)
printf("%d\t",queue[i]);
}
}