Queue implementation C++ -


hi creating queue assignment have , keep getting output of " 4 4 4 4 4 ". not sure if doing queue wrong on paper or if messed in program. want confirm if queue come out output. included enqueue , dequeue files. thank you

#include <iostream> #include <cstdlib> using namespace std;  const int max_size = 100;  class queueoverflowexception { public:    queueoverflowexception()    {        cout << "queue overflow" << endl;    } };  class queueemptyexception { public:    queueemptyexception()    {        cout << "queue empty" << endl;    } };  class arrayqueue { private:    int data[max_size];    int front;    int rear; public:    arrayqueue()    {        front = -1;        rear = -1;    }     void enqueue(int element)    {        // don't allow queue grow more        // max_size - 1        if ( size() == max_size - 1 )            throw new queueoverflowexception();         data[rear] = element;         // mod used rear indicator        // can wrap around        rear = ++rear % max_size;    }     int dequeue(int n)    {        if ( isempty() )            throw new queueemptyexception();         int ret = data[front];         // mod used front indicator        // can wrap around        front = ++front % max_size;         return ret;    }     int front()    {        if ( isempty() )            throw new queueemptyexception();         return data[front];    }     int size()    {        return abs(rear - front);    }     bool isempty()    {        return ( front == rear ) ? true : false;    } };  int main() {    arrayqueue q;     int x =2;    int y = 4;     q.enqueue(x);    q.enqueue(y);    q.dequeue(x);    q.enqueue(x+5);    q.enqueue(16);    q.enqueue(x);    q.enqueue(y-3);     cout << "queue: ";     while(!q.isempty())    {        q.dequeue(y);        cout<<" " << y;    } }

your code have following bugs.

  1. in enqueue, first rear should incremented , value should inserted.
  2. dequeue function should not take argument.
  3. in main function calling dequeue function in wrong manner. dequeue function returns integer should either store return value in variable or output directly output screen using cout.

correct code is:

    #include <iostream>     #include <cstdlib>     using namespace std;      const int max_size = 100;      class queueoverflowexception     {         public:            queueoverflowexception()            {                cout << "queue overflow" << endl;            }     };      class queueemptyexception     {         public:            queueemptyexception()            {                cout << "queue empty" << endl;            }     };      class arrayqueue     {         private:            int data[max_size];            int front;            int rear;         public:            arrayqueue()            {                front = -1;                rear = -1;            }         void enqueue(int element)        {            // don't allow queue grow more            // max_size - 1            if ( size() == max_size - 1 )                throw new queueoverflowexception();             // mod used rear indicator            // can wrap around            rear = ++rear % max_size;            data[rear] = element;          }         int dequeue()        {            if ( isempty() )                throw new queueemptyexception();             int ret = data[front];             // mod used front indicator            // can wrap around            front = ++front % max_size;             return ret;        }         int front()        {            if ( isempty() )                throw new queueemptyexception();             return data[front];        }         int size()        {            return abs(rear - front);        }         bool isempty()        {            return ( front == rear ) ? true : false;        }     };      int main()     {        arrayqueue q;         int x =2;        int y = 4;         q.enqueue();        q.enqueue(y);        q.dequeue();        q.enqueue(x+5);        q.enqueue(16);        q.enqueue(x);        q.enqueue(y-3);         cout << "queue: ";         while(!q.isempty())        {            cout<<q.dequeue();        }     }

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