#include <iostream.h>
#include <string.h>

const int MAXCHARS = 30;
const int TRUE = 1;
const int FALSE = 0;

// class declaration

// preconditions: requires that MAXCHARS, the maximum size of a name, be defined
//              : requires that TRUE be defined as a nonzero integer
//              : requires that FALSE be defined as 0

class Queue
{
  private:
    struct NameRec
    {
     char name[MAXCHARS];
     NameRec *nextaddr;
    };
    NameRec *queueIn;  // top-of-queue pointer
    NameRec *queueOut; // bottom-of-queue pointer

  public:
    Queue();   // constructor
    void enque(char *);
    char *serve();
    int isempty();
};

// implementation section

Queue::Queue()   // constructor
{
  queueIn = NULL;
  queueOut = NULL;
}

void Queue::enque(char *newname)
{
  NameRec *newAddr;  // a pointer to a NameRec

  newAddr = new (NameRec);
  if (newAddr == NULL)
  {
    cout << "\No more storage allocation space"
      << "\nThe last name has not been entered on the queue"
      << endl;
  }
  else
  {
    strcpy(newAddr->name, newname);   // store the name
    newAddr->nextaddr = NULL;         // set the address to NULL
       // empty queue checks
    if(queueIn != NULL)    // can be replaced by if(!isempty())
      queueIn->nextaddr = newAddr;
    if (queueOut == NULL)   // can be replaced by if(isempty())
       queueOut = newAddr;
    queueIn  = newAddr;
  }

  return;
}

char *Queue::serve()
{
  NameRec *tempAddr;
  char name[MAXCHARS];

  strcpy(name, queueOut->name);  // retrieve the name from queue bottom
  tempAddr = queueOut->nextaddr;  // retrieve next address
  delete(queueOut);                // free record's memory space
  queueOut = tempAddr;        // update the bottom-of-queue pointer
  return name;
}

int Queue::isempty()
{
  if (queueOut == NULL)
    return TRUE;
  else
    return FALSE;
}

int main()
{
  char newname[MAXCHARS];
  Queue namequeue;   // define a Queue object

  cout << "Enter as many names as you wish, one per line"
       << "\nTo stop entering names, enter a single x\n";
  while (1)
  {
    cout << "Enter a name: ";
    cin.getline(newname,MAXCHARS);
    if (strcmp(newname,"x") == 0)
      break;
    else
      namequeue.enque(newname);
  }

    // serve and display names from the queue
  cout << "\nThe names served from the queue are:\n";
  while(!namequeue.isempty())   // display till end of queue
  {
    strcpy(newname, namequeue.serve());
    cout << newname << endl;
  }

  return 0;
}