Dequeue in DSA using Pointer

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

#define SIZE 5//its value remains constant

//Declaration of structure
typedef struct deque
{
     int Arr[SIZE];
     int front;
     int rear;
}deque;

/* Declaration of functions */

//Function to display the menu
void menu();

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

//Function to add an element in the beginning
int enqueBeg(deque *,int );

//Function to add an element in the end
int enqueEnd(deque *,int );

//Function to serve an element from the beginning
int dequeueBeg(deque *,int *);

//Function to serve an element from the end
int dequeueEnd(deque *,int *);

//Function to check if the deque is empty
int IsEmpty(deque );

//Function to check if the deque is full
int IsFull(deque );

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

void main()
{
  clrscr();
  menu(); //Function call
  getch();
}

void menu()
{
  deque dq;
  int info,choice,call,flag;
  call=flag=0;

  //To initialise..
  initdeque(&dq); //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. IsEmpty\n");
       printf("  6. IsFull\n");
       printf("  7. Display\n");
       printf("  8. 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);
   
                    call=enqueBeg(&dq,info); //Function call for adding at the beginning.

    if(call)//if some value is returned other than zero.
printf("Element added in the beginning!");

    else
printf("Element can't be added!");

    getch();
    break;

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


    call=enqueEnd(&dq,info); //Function call[En-queue/Append in the end]
    if(call)//if some value is returned other than zero.
printf("Element added in the end!");
    else
printf("Element can't be added!");

    getch();
    break;

   case 3:  info=dequeueBeg(&dq,&flag); //Function call for deleitng from begining.[De-queue/Serve from the beginning]

    if(flag)
printf("Popped out element is %i",info);
    else
printf("Element can't be popped out from the beginning!");
    getch();
    break;

   case 4:  info=dequeueEnd(&dq,&flag); //Function call  for deleitng at the end.[De-queue/Serve from the end]
    if(flag)
printf("Popped out element is %i",info);
    else
printf("Element can't be popped out from the end!");

    getch();
    break;

   case 5:  if(IsEmpty(dq)) //Function call
printf("Deque is empty!");
    else
printf("Deque is not empty!");

    getch();
    break;

   case 6:  if(IsFull(dq)) //Function call
printf("Deque is full!");
    else
printf("Deque is not full!");

//Note:We can implement isFull() and isEmpty() using bool concept also in which we return
//true and false values only.
    getch();
    break;

   case 7:  display(dq); //Function call

    getch();
    break;

   case 8:  exit();

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


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


int enqueBeg(deque *deq,int info)
{
   int i;

   //To check if the queue is full
   if(deq->front==0 && deq->rear==SIZE-1) //If the queue is full...
      return 0; //...element can't be added in deque


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

deq->Arr[deq->front]=info;

return 1; //Flag success to the function
      }

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

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

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

      }


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

//...new element will be accomodated in the empty cell
deq->Arr[deq->front]=info;
      }
   return 1;
}


int enqueEnd(deque *deq,int info)
{
   int i;

   //To check if the queue is full
   if(deq->front==0 && deq->rear==SIZE-1) //If the queue is full...

      return 0; //...element can't be added in deque

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

return 1; //Flag success to the function
      }

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


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

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

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


int dequeueBeg(deque *deq,int *flag)
{
   int info;

   //If the deque is empty...
   if(deq->front==-1)
      {
*flag=0; //...no element can be served
return 0; //End of function
      }

   //Else
   //Extracting info & setting flag
   info=deq->Arr[deq->front];
   deq->Arr[deq->front]=0;

   *flag=1; //Success


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

   else
      deq->front++; //Front cell is unoccupied now

   return info; //Returning the info
}


int dequeueEnd(deque *deq,int *flag)
{
   int info;


   //If the deque is empty...
   if(deq->front==-1)
      {
*flag=0; //...no element can be served
return 0; //End of function
      }

   //Else
   //Extracting info & setting flag
   info=deq->Arr[deq->rear];

   deq->Arr[deq->rear]=0;

   *flag=1; //Success

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

   return info; //Returning the info
}


int IsEmpty(deque deq)
{
   if(deq.front==-1)
      return 1; //Is empty
   else
      return 0; //Is not empty
}


int IsFull(deque deq)
{
   if(deq.front==0 && deq.rear==SIZE-1)
      return 1; //Is full
   else
      return 0; //Is not full
}

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

   //If the deque is empty...
   if(IsEmpty(deq))
      {
printf("The deque is empty!");
return; //...end of function
      }

   //Displaying the deque elments
   for(i=(deq.front);i<=(deq.rear);i++)
      printf("%i\t",deq.Arr[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. IsEmpty
 6. IsFull
  7. Display
  8. Exit
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. IsEmpty
 6. IsFull
  7. Display
  8. 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. IsEmpty
 6. IsFull
  7. Display
  8. Exit
Your choice:
3

popped out element is
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. IsEmpty
 6. IsFull
  7. Display
  8. Exit
4
popped out element is
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. IsEmpty
 6. IsFull
  7. Display
  8. Exit
Your choice:
8


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