C program to implement input and output restricted deques

#include <stdio.h>
#include <conio.h>
#define MAX 10
int deque[MAX];
int left = –1, right = –1;
void input_deque(void);
void output_deque(void);
void insert_left(void);
void insert_right(void);
void delete_left(void);
void delete_right(void);
void display(void);
int main()
{
int option;
clrscr();
printf("\n *****MAIN MENU*****");
printf("\n 1.Input restricted deque");
printf("\n 2.Output restricted deque");
printf("Enter your option : ");
scanf("%d",&option);
switch(option)
{
 case 1:
 input_deque();
break;
 case 2:
 output_deque();
break;
}
return 0;
}
void input_deque()
{
int option;
do
{
 printf("\n INPUT RESTRICTED DEQUE");
 printf("\n 1.Insert at right");
 printf("\n 2.Delete from left");
 printf("\n 3.Delete from right");
 printf("\n 4.Display");
 printf("\n 5.Quit");
 printf("\n Enter your option : ");
 scanf("%d",&option);
switch(option)
 {
 case 1:
 insert_right();
break;
 case 2:
 delete_left();
break;
 case 3:
 delete_right();
break;
 case 4:
 display();
break;
 }
}while(option!=5);

}
void output_deque()
{
int option;
do
{
 printf("OUTPUT RESTRICTED DEQUE");
 printf("\n 1.Insert at right");
 printf("\n 2.Insert at left");
 printf("\n 3.Delete from left");
 printf("\n 4.Display");
 printf("\n 5.Quit");
 printf("\n Enter your option : ");
 scanf("%d",&option);
switch(option)
 {
 case 1:
 insert_right();
break;
 case 2:
 insert_left();
break;
 case 3:
 delete_left();
break;
 case 4:
 display();
break;
 }
}while(option!=5);
}
void insert_right()
{
int val;
printf("\n Enter the value to be added:");
scanf("%d", &val);
if((left == 0 && right == MAX–1) || (left == right+1))
{
 printf("\n OVERFLOW");
 return;
}
if (left == –1) /* if queue is initially empty */
{
left = 0;
right = 0;
}
else
{
 if(right == MAX–1) /*right is at last position of queue */
right = 0;
 else
 right = right+1;
}
deque[right] = val ;
}
void insert_left()
{
int val;
printf("\n Enter the value to be added:");
scanf("%d", &val);
if((left == 0 && right == MAX–1) || (left == right+1))
{
 printf("\n Overflow");
 return;
}

if (left == –1)/*If queue is initially empty*/
{
left = 0;
right = 0;
}
else
{
if(left == 0)
 left=MAX–1;
 else
 left=left–1;
}
deque[left] = val;
}
void delete_left()
{
if (left == –1)
{
 printf("\n UNDERFLOW");
 return ;
}
printf("\n The deleted element is : %d", deque[left]);
if(left == right) /*Queue has only one element */
{
 left = –1;
 right = –1;
}
else
{
 if(left == MAX–1)
left = 0;
 else
 left = left+1;
}
}
void delete_right()
{
if (left == –1)
{
 printf("\n UNDERFLOW");
 return ;
}
printf("\n The element deleted is : %d", deque[right]);
if(left == right) /*queue has only one element*/
{
 left = –1;
 right = –1;
}
else
{
if(right == 0)
 right=MAX–1;
 else
 right=right–1;
}
}
void display()
{
int front = left, rear = right;
if(front == –1)
{
 printf("\n QUEUE IS EMPTY");
 return;
}
printf("\n The elements of the queue are : ");

if(front <= rear )
{
while(front <= rear)
 {
 printf("%d",deque[front]);
front++;
 }
}
else
{
while(front <= MAX–1)
 {
 printf("%d", deque[front]);
front++;
 }
front = 0;
while(front <= rear)
 {
 printf("%d",deque[front]);
front++;
 }
}
printf("\n");
}

***** MAIN MENU *****
1.Input restricted deque
2.Output restricted deque
Enter your option : 1
INPUT RESTRICTED DEQUEUE
1.Insert at right
2.Delete from left
3.Delete from right
4.Display
5.Quit
Enter your option : 1
Enter the value to be added : 5
Enter the value to be added : 10
Enter your option : 2
The deleted element is : 5
Enter your option : 5