Program to implement a Queue using Array by incrementing front as well as rear

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/*Implementation of Linear queues using arrays*/
/*Queue implementation by shifting front as well as rear*/

#include <iostream.h>
#include <conio.h>
#include <stdio.h>
#define max 5

int front,rear,q[max];
void enqueue(void);
void dequeue(void);
void qdisplay(void);
void main(void)
{
     int c;
     clrscr();
     front=rear=-1;
     do
     {
          printf("1:insert\n2:deletion\n3:display\n4:exit\nenter choice:");
          scanf("%d",&c);
//C program to implement circular Queue using Array
switch(c)
          {
               case 1:enqueue();break;
               case 2:dequeue();break;
               case 3:qdisplay();break;
               case 4:printf("pgm ends\n");break;
               default:printf("wrong choice\n");break;
          }
     }while(c!=4);
     getch();
}
void enqueue(void)
{
     int x;
     if((front==0&&rear==max-1)||(front==rear+1))                         //condition for full Queue
     {
          printf("Queue is overflow\n");return;
     }
     if(front==-1)
     {
          front=rear=0;
     }
     else
     {
          if(rear==max-1)
          {
               rear=0;
          }
          else
          {
               rear++;
          }
     }
     printf("enter the no:\n");
     scanf("%d",&x);
     q[rear]=x;
     printf("%d succ. inserted\n",x);
     return;
}
void dequeue(void)
{
     int y;
     if(front==-1)
     {
          printf("q is underflow\n");return;
     }
     y=q[front];
     if(front==rear)
     {
          front=rear=-1;
     }
     else
     {
          if(front==max-1)
          {
               front=0;
          }
          else
          {
               front++;
          }
     }
     printf("%d succ. deleted\n",y);
     return;
}
void qdisplay(void)
{
     int i,j;
     if(front==rear==-1)
     {
          printf("q is empty\n");return;
     }
     printf("elements are :\n");
     for(i=front;i!=rear;i=(i+1)%max)
     {
          printf("%d\n",q[i]);
     }
     printf("%d\n",q[rear]);
     return;
}