cq.c

#include<stdio.h>
#include<conio.h>
#include<stdlib.h>
#define SIZE 5

void enQueue(int);
void deQueue();
void display();

int cQueue[SIZE], front = -1, rear = -1, l = 0;

void main()
{
   printf("Enter length of the array:");
   scanf("%d", &l);
   cQueue[l];
   int choice, value;
   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("\nEnter the value to be insert:  ");
		 scanf("%d",&value);
		 enQueue(value);
		 break;
	 case 2: deQueue();
		 break;
	 case 3: display();
		 break;
	 case 4: exit(0);
	 default: printf("\nPlease select the correct choice!!!\n");
      }
   }
}
void enQueue(int value)
{
   if((front == 0 && rear == l - 1) || (front == rear+1))
      printf("\nCircular Queue is Full! Insertion not possible!!!\n");
   else{
      if(rear == l-1 && front != 0)
	 rear = -1;
      cQueue[++rear] = value;
      printf("\nInsertion Success!!!\n");
      if(front == -1)
	 front = 0;
   }
}
void deQueue()
{
   if(front == -1 && rear == -1)
      printf("\nCircular Queue is Empty! Deletion is not possible!!!\n");
   else{
      printf("\nDeleted element : %d\n",cQueue[front++]);
      if(front == l)
	 front = 0;
      if(front-1 == rear)
	 front = rear = -1;
   }
}
void display(){
    int i = 0;
    if(front == -1)
        printf("\nCircular Queue is Empty!!!\n");
    else{
        printf("\n Elements:");
        for(i = front; i != rear; i = (i+1)%l)
            printf("%d\t", cQueue[i]);
        printf("%d", cQueue[i]);
    }
}