De-Queue in DSA using Arrays

/* Program to implement deque using arrays*/
//include header files
#include<stdio.h>
#include<conio.h>

     int deque[5];
    long front,rear;



//Function to initialise the deque
void initdeque();

//Function to add an element in the beginning
void enqueBeg(int);

//Function to add an element in the end
void enqueEnd(int );

//Function to serve an element from the beginning
void dequeueBeg();

//Function to serve an element from the end
void dequeueEnd();

//Function to display the deque elements
void display ( );



void main()
{
 int info,choice;

  //To initialise..
  initdeque(); //Function call

while(1)//at least it will run for once
     {
       //Displaying menu
       clrscr();
       printf("        MENU\n");
       printf("1. En-queue/Append in the beginning\n");
       printf("2. En-queue/Append in the end\n");
       printf("3. De-queue/Serve from the beginning\n");
       printf("4. De-queue/Serve from the end\n");
       printf("5. Display\n");
       printf("6. Exit\n");

       printf("Your choice: ");
       scanf("%i",&choice);

switch(choice)
 {
   case 1:  printf("Enter the element to be added in the beginning:");
    scanf("%i",&info);

   enqueBeg(info); //Function call for adding at the beginning.

    getch();
    break;

   case 2:  printf("Enter the element to be added in the end: ");
    scanf("%i",&info);

    enqueEnd(info); //Function call[En-queue/Append in the end]

    getch();
    break;

   case 3:  dequeueBeg(); //Function call for deleitng from begining.[De-queue/Serve from the beginning]

    getch();
    break;

   case 4:  dequeueEnd(); //Function call  for deleitng at the end.[De-queue/Serve from the end]
    getch();
    break;

   case 5:  display(); //Function call
    getch();
    break;

   case 6:  exit();
                                      break;

   default: printf("You entered wrong choice!");
    getch();
 }
     }
}


void initdeque()//initialising the deque.
{
   front=rear=-1;
}


void enqueBeg()
{
   int i,info;


   //If dequeue is empty then first element can be simply added
   if(front==-1)
      {
front=rear=0;//both fornt,rear point to first element.

deque[front]=info;

      }

   //If the deque is full from the front only...
   if(front==0 && rear!=5-1)
      {
//...shift the elements from 1 posn to it's right
for(i=rear;i>=front;i--)
  deque[i+1]=deque[i];

//Index no. of last element should be incremented after shifting
       rear++;

        //New element will be added in the front of deque
deque[front]=info;

      }


   //if the deque is empty from the front...
   else if(front>0)
      {
front--;

//...new element will be accomodated in the empty cell
deque[front]=info;
      }

}


void enqueEnd()
{
   int i,info;

   //If dequeue is empty then first element can be simply added
   if(front==-1)
      {
front=rear=0;
deque[front]=info;

      }

   //If the deque is full from the end only...
   if(front!=0 && rear==5-1)
      {
//...shift the elements from 1 posn to its left
for(i=front;i<=rear;i++)
  deque[i-1]=deque[i];


//Index no. of first element should be decremented after shifting
front++;

//New element will be added in the end of deque
deque[rear]=info;
      }

   //if the deque is empty from the end...
   else if(rear<5-1)
      {
rear++;
//...new element will be accomodated in the empty cell
deque[rear]=info;
      }
   return 1;
}


void dequeueBeg()
{
   int info;

   //If the deque is empty...
   if(front==-1)
      {
return 0; //End of function
      }

   //Else
   //Extracting info & setting flag
   info=deque[front];
   deque[front]=0;

   //Setting front
   if(front==rear)
      front=rear=-1; //As the deque will become empty

   else
      front++; //Front cell is unoccupied now

   return info; //Returning the info
}


void dequeueEnd()
{
   int info;

   //If the deque is empty...
   if(front==-1)
      {
return 0; //End of function
      }

   //Else
   //Extracting info & setting flag
   info=deque[rear];

deque[rear]=0;

   //Setting rear
   if(front==rear)
           front=rear=-1; //As the deque will become empty
   else
      rear--; //Rear cell is unoccupied now

   return info; //Returning the info
}


/*displays the curent position of the dqueue*/
void display ()
{
   int i;

   //Displaying the deque elments
   for(i=front;i<=rear;i++)
      printf("%i\n",deque[i]);
}


/*output of the program*/
 MENU
1. En-queue/Append in the beginning
2. En-queue/Append in the end
3. De-queue/Serve from the beginning
4. De-queue/Serve from the end
5. Display
Your choice
1

enter the element to be added at the beginning
5
        MENU
1. En-queue/Append in the beginning
2. En-queue/Append in the end
3. De-queue/Serve from the beginning
4. De-queue/Serve from the end
5. Display
6. Exit
Your choice:
2

enter the element to be added at the end
50



        MENU
1. En-queue/Append in the beginning
2. En-queue/Append in the end
3. De-queue/Serve from the beginning
4. De-queue/Serve from the end
5. Display
6. Exit
Your choice:
3

enter the element to be deleted from the beginning
5


        MENU
1. En-queue/Append in the beginning
2. En-queue/Append in the end
3. De-queue/Serve from the beginning
4. De-queue/Serve from the end
5. Display
6. Exit
Your choice:
4

enter the element to be deleted from the end
50


        MENU
1. En-queue/Append in the beginning
2. En-queue/Append in the end
3. De-queue/Serve from the beginning
4. De-queue/Serve from the end
5. Display
6. Exit
Your choice:
6

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