circular queue

This is a discussion on circular queue within the C++ Programming forums, part of the General Programming Boards category; Hello everyone. I am trying to create a circular queue and need some pointers. My questions are as follows: 1. ...

  1. #1
    Registered User
    Join Date
    May 2004
    Posts
    4

    circular queue

    Hello everyone. I am trying to create a circular queue and need some pointers. My questions are as follows:

    1. Will my queue class produce a circular queue?

    2. The random contributors are not being added correctly to the queue. When I dequeue() the queue, it thinks it carries default values assigned from my constructor.


    All help is greatly appreciated.

    Here is the code:

    main.cpp:
    Code:
    #include <iostream>
    #include <ctime>
    #include <cstdlib>
    using namespace std;
    
    #include "contributor.h"
    #include "queue.h"
    
    int main()
    {
    	MyQueue Q;
    	
    	double Con,ID;
    	short Sex;
    	
    	srand(time(0));
    	for(int j = 0; j < Q.getSize(); j++)
    	{
    		Con = rand() % 1000 + 1;
    		Sex = rand() % 10 + 1;
    		ID = rand() % 100 + 1;
    		if (Sex > 4)
    			Q.Enqueue(Contributor("Random Male",male,Con,ID));
    		else
    			Q.Enqueue(Contributor("Random Female",female,Con,ID));
    		cout << Q.Dequeue() << endl;
    	}
    	cout << "Size = " << Q.getSize() << endl;
    	cout << Q.ShowFront() << endl;
    		
    	return 0;
    }
    queue.h:
    Code:
    #ifndef QUEUE_H
    #define QUEUE_H
    
    #include "contributor.h"
    
    class MyQueue
    {
    public:
    	MyQueue();
    	~MyQueue(){delete [] mArray;}
    	void Enqueue(Contributor &);
    	const Contributor & Dequeue();
    	const Contributor & ShowFront() const{return mArray[mFront];}
    	bool Is_Empty() const{return mFront == mRear;}
    	bool Is_Full() const{return mRear + 1 % MaxSize == mFront;}
    	short getSize() const{return MaxSize;}
    	
    private:
    	int mSize,mFront,mRear;
    	short MaxSize;
    	Contributor *mArray;
    };
    
    #endif
    queue.h:
    Code:
    #include <iostream>
    #include <cstdlib>
    #include <ctime>
    #include <stack>
    using namespace std;
    
    #include "queue.h"
    #include "contributor.h"
    
    MyQueue::MyQueue()
    {
    	MaxSize = 25;
    	mArray = new Contributor[MaxSize];
    	mRear = mFront = mSize = 0;
    }
    
    void MyQueue::Enqueue(Contributor &cont)
    {
    	if (!Is_Full())
    	{
    		mArray[mRear] = cont;
    		mRear = (mRear + 1) % MaxSize;
    		mSize++;
    	}
    	else
    		cout << "ERROR: could not add to the queue - queue is full." << endl;
    }
    
    const Contributor & MyQueue::Dequeue()
    {
    	if (!Is_Empty())
    	{
    		mFront = (mFront + 1) % MaxSize;
    		return mArray[mFront];
    		mSize--;
    	}
    	else
    	{
    		cout << "ERROR: could not remove from the queue - queue is empty." << endl;
    		exit(1);
    	}
    }
    contributor.h:
    Code:
    #ifndef CONTRIBUTOR_H
    #define CONTRIBUTOR_H
    
    enum Gender_type {male,female,unknown};
    
    class Contributor
    {
    public:
    	Contributor();
    	Contributor(string,Gender_type,double,int);
    	Contributor(const Contributor &);
    	~Contributor ();
    
    	friend ostream & operator<< (ostream &, const Contributor &);
    	friend istream & operator>> (istream &, Contributor &);
    
    	const Contributor & operator= (const Contributor &);
    		
    	string getName(){return Name;}
    	double getContribution(){return Contribution;}
    	int getIDKey(){return IDKey;}
    	Gender_type getGender(){return Gender;}
    	short getGender1();
    
    	bool operator< (const Contributor &) const;
    	bool operator> (const Contributor &) const;
    	bool operator>= (const Contributor &) const;
    	bool operator== (const Contributor &) const;
    	bool operator!= (const Contributor &) const;
    
    private:
    	string Name;
    	double Contribution;
    	int IDKey;
    	Gender_type Gender;
    };
    
    #endif
    contributor.cpp:
    Code:
    #include <iostream>
    #include <cstdlib>
    #include <ctime>
    #include <string>
    using namespace std;
    
    #include "queue.h"
    #include "contributor.h"
    
    Contributor::Contributor()
    {
    	Contribution = 0.00;
    	Name = "Blank";
    	Gender = unknown;
    	IDKey = 0;
    }
    Contributor::Contributor(string name,Gender_type g,double contribution,int idkey)
    {
    	Name = name;
    	Gender = g;
    	Contribution = contribution;
    	IDKey = idkey;
    }
    Contributor::Contributor(const Contributor &c)
    {
    	Name = c.Name;
    	Gender = c.Gender;
    	Contribution = c.Contribution;
    	IDKey = c.IDKey;
    }
    
    Contributor::~Contributor () 
    {}
    
    ostream & operator<< (ostream &out, const Contributor &c)
    {
    	string temp;
    	if (c.Gender == male)
    		temp = "male  ";
    	if (c.Gender == female)
    		temp = "female";
    	if (c.Gender == unknown)
    		temp = "unknown";
    	out << "Name = " << c.Name << "\tGender = " << temp << "\t" << "Contribution = " << "$" << c.Contribution << ".00" << "\t" << "IDKey = " << c.IDKey;
    	return out;
    }
    
    istream & operator>> (istream &in, Contributor &r)
    {
    	string temp;
    	cout << "Enter a name (no spaces): ";
    	in >> r.Name;
    	cout << "Enter gender (male, female, unknown): ";
    	in >> temp;
    	if (temp == "male")
    		r.Gender = male;
    	if (temp == "female")
    		r.Gender = female;
    	if (temp == "unknown")
    		r.Gender = unknown;
    	if (temp != "unknown" && temp != "male" && temp != "female")
    		r.Gender = unknown;
    	cout << "Enter a contribution: ";
    	in >> r.Contribution;
    	cout << "Enter an ID Key: ";
    	in >> r.IDKey;
    	return in;
    }
    
    const Contributor & Contributor::operator= (const Contributor &rhs)
    {
    	Contribution = rhs.Contribution;
    	Name = rhs.Name;
    	Gender = rhs.Gender;
    	IDKey = rhs.IDKey;
    	return *this;
    }
    
    bool Contributor::operator< (const Contributor &rhs) const
    {
    	return (Contribution < rhs.Contribution);
    }
    bool Contributor::operator> (const Contributor &rhs) const
    {
    	return (Contribution > rhs.Contribution);
    }
    bool Contributor::operator>= (const Contributor &rhs) const
    {
    	return (Contribution >= rhs.Contribution);
    }
    bool Contributor::operator== (const Contributor &rhs) const
    {
    	return (Name == rhs.Name);
    }
    bool Contributor::operator!= (const Contributor &rhs) const
    {
    	return (Name != rhs.Name);
    }
    
    short Contributor::getGender1() 
    {
    	if (getGender() == male)
    		return 0;
    	if (getGender() == female)
    		return 1;
    	else
    		return 2;
    }

  2. #2
    Normal vector Carlos's Avatar
    Join Date
    Sep 2001
    Location
    Budapest
    Posts
    463
    Why reinvent the wheel?
    STL queue and deque containers won't do it for you?

  3. #3
    Code Goddess Prelude's Avatar
    Join Date
    Sep 2001
    Posts
    9,796
    >1. Will my queue class produce a circular queue?
    Good question. Will it? You sound like you have no confidence in the code that you've written. I would recommend removing all unnecessary code from the Queue class so that you can test it thoroughly using something simple, like integers:
    Code:
    class Queue {
    public:
      Queue(int max_size);
      ~Queue();
    public:
      void enqueue(int val);
      int  dequeue();
    private:
      int *vals;
      int  size;
      int  front;
      int  rear;
    };
    
    Queue::Queue(
      int max_size
      )
      : size(max_size + 1)
      , front(max_size + 1)
      , rear(0)
    {
      vals = new int[size];
    }
    
    Queue::~Queue()
    {
      delete [] vals;
    }
    
    void
    Queue::enqueue(
      int val
      )
    {
      if (rear % size + 1 == front) {
        throw -1;
      }
      vals[rear++] = val;
      if (rear == size) {
        rear = 0;
      }
    }
    
    int
    Queue::dequeue()
    {
      if (front % size == rear) {
        throw -2;
      }
      if (front == size) {
        front = 0;
      }
      return vals[front++];
    }
    Once you're confident in your queue's correctness, the other problem should be easier to debug if it still exists.
    My best code is written with the delete key.

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