C program to implement Circular queue using array

C program to implement Circular queue using array

#include <stdio.h>
#include <conio.h>
#include <malloc.h>
#include <process.h>
#include <ctype.h>
#define SIZE 10

void menu();
void display();
int underflow();
int overflow();
void enqueue(int);
void dequeue();
int cqueue[SIZE];
int front=-1;
int rear=-1;

void main()
{
 clrscr();
 menu();
}
 
void menu()
{
 int choice,item;
 printf("MENU");
 printf("n1. Insert into the queue");
 printf("n2. Delete from queue");
 printf("n3. Display");
 printf("n4. Exit");
 printf("nEnter your choice: ");
 scanf("%d",&choice);
 switch(choice)
 {
  case 1:
  clrscr();
  if(overflow()==0)
  {
   printf("nEnter the item tobe inserted: ");
   scanf("%d",&item);
   enqueue(item);
   clrscr();
   printf("nAfter inserting queue is:n");
  }
  display();
  getch();
  clrscr();
  menu();
  break;
 
  case 2:
  clrscr();
  if(underflow()==1)
  {
   dequeue();
   if(underflow()==1)
   {
    printf("nAfter deletion queue is:n");
    display();
   }
  }
  getch();
  clrscr();
  menu();
  break;
  
  case 3:
  clrscr();
  if(underflow()==1)
  { 
   printf("The queue is:n");
   display();
  }
  getch();
  clrscr();
  menu();
  break;
     
  case 4:
  exit(1);
  default:
  clrscr();
  printf("Your choice is wrongnn");
  menu();

 }
}
 
int underflow()
{
 if((front==-1)&&(rear==-1))
 {
  printf("nQueue is empty");
  return(0);
 }
 else
 {
  return(1);
 }
}
 
int overflow()
{
 if(((front==0)&&(rear==SIZE-1))||(front==rear+1))
 {
  printf("nQueue is fulln");
  return(1);
 }
 else
 {
  return(0);
 }
}
 
void enqueue(int item)
{
 if((front==-1)&&(rear==-1))
 {
  front=0;
  rear=0;
 }
 else if(rear==SIZE-1)
 {
  rear=0;
 }
 else
 {
  rear=rear+1;
 }
 cqueue[rear]=item;
}

void dequeue()
{
 if(front==rear)
 {
  front=-1;
  rear=-1;
 }
 else if(front==SIZE-1)
 {
  front=0;
 }
 else
 {
  front=front+1;
 }
}

void display()
{
 int i;
 if(front<=rear)
 {
  for(i=front;i<=rear;i++)
  {
   printf("nElement %d : %d",i+1,cqueue[i]);
  }
 }
 else
 {
  for(i=front;i<=SIZE-1;i++)
  {
   printf("nElement %d : %d",i+1,cqueue[i]);
  }
  for(i=0;i<=rear;i++)
  {
   printf("nElement %d : %d",i+1,cqueue[i]);
  }
 }
}