Write a member function length to compute the number of item

Write a member function length to compute the number of items in a queue containing positive integers. The queue must be unchanged. You can use all queue member functions as discussed in class. The calling statement shall look like q.length(..) where q is declared as follows: queue q;

Solution

#include<iostream>
#include<cstdlib>
#define default_value 16
using namespace std;
template< class T > class queue //template class for queue
{
public:
queue(int = default_value);//default constructor
~queue()//destructor
{delete [] values;}
bool enQueue( T );
T deQueue();
bool isEmpty();
bool isFull();
int length();
private:
int size;
T *values;
int front;
int back;
       int no_of_element_in_queue;
};

template< class T > queue<T>::queue(int x): //initialization of default values
size(x),
values(new T[size]),
front(0),
back(0),
no_of_element_in_queue(0)
{ /*empty*/ }

template< class T > bool queue<T>::isFull() //function returns true if queue is full
{
if((back + 1) % size == front ) //if there is no gap between back and front
return 1;
else
return 0;
}

template< class T > int queue<T>::length()
{
int count=0,i=0;
while(i < no_of_element_in_queue) //for all elements in queue
if(values[i++] > 0) //if the value is
count++;
return count;
}

template< class T > bool queue<T>::enQueue(T x)
{
bool b = 0;
if(!queue<T>::isFull())
{
values[back] = x;
back = (back + 1) % size;
b = 1;
   no_of_element_in_queue++;
}
return b;
}

template< class T > bool queue<T>::isEmpty()
{
if( back == front )//is empty
return 1;
else
return 0; //is not empty
}

template< class T > T queue<T>::deQueue()
{
T val = -1;
if(!queue<T>::isEmpty())
{
val = values[front];
front = ( front + 1 ) % size;
       no_of_element_in_queue--;
}
else
{
cerr << \"queue is Empty : \";
}
return val;
}

int main()
{
queue <int> q;
q.enQueue(32);
q.enQueue(0);
q.enQueue(-17);
q.enQueue(52);
cout<<\"\ \"<<q.length();
q.deQueue();
q.deQueue();
cout<<\"\ \"<<q.length();
return 0;
}