#Code

#ifndef PQueue_H
#define PQueue_H
#include <cmath>
#include <iostream>
const int maxsize = 5;
template <class T>
class PQueue
{
 T items[maxsize];
 int front, rear,n;
public:
 PQueue(T val);
 PQueue(const PQueue<T>& q);
 ~PQueue();
 void insert(T x, int& overflow);
 int search_position(T x);
 T remove(int& underflow);
 T first(int& underflow) const;
 T last(int& underflow) const;
 int size() const;
 bool empty() const;
 void print () const;
 void increment(int& i);
 void decrement(int& i);
};
template <class T>
PQueue<T>::PQueue(T val)
{
 for (int i = 0; i < maxsize; i++)
 items[i] = val;
 front = rear = maxsize - 1;
 n = 0;
}
template <class T>
PQueue<T>::PQueue(const PQueue<T>& q)
{
 for (int i = 0; i < q.n; i++)
 {
 items[i] = q.items[i];
 }
 front = rear = maxsize - 1;
 n = 0;
}
template <class T>
PQueue<T>::~PQueue() {};
template <class T>
int PQueue<T>::search_position(T x)
{
 int low = front, high = rear;
 int i;
 if (empty()) {
 return (rear+1)%maxsize;
 }
 
 for (i = (front+1)%maxsize; i != (rear+1)%maxsize; increment(i))
 { 
 if (items[i] > x)
 break;
 }
 return i;
}
template <class T>
void PQueue<T>::insert(T x, int& overflow)
{
 overflow = 0;
 if ((rear + 1) % maxsize == front)
 {
 overflow = 1;
 return;
 }
 else
 {
 int index = search_position(x);
 std::cout << "\nInserting item " << x << " at position " << index;
 increment(rear);
 //If index matches the updated value of rear,
 //there must be nothing to shift.
 if(index!=rear)
 {
 int i = rear - 1, j = rear;
 i += maxsize; i %= maxsize;
 j += maxsize; j %= maxsize;
 do
 {
 //Shift all elements 1 position to 
 //the right in item[index...rear]
 items[j] = items[i];
 std::cout << "\nShifting item " << items[i] << " from index "
 << i << " to " << j;
 decrement(i); 
 decrement(j);
 } while (j != index);
 }
 n++;
 items[index] = x;
 }
}
template <class T>
T PQueue<T>::remove(int& underflow)
{
 underflow = 0;
 if (empty())
 {
 underflow = 1;
 return -1;
 }
 else
 {
 increment(front);
 std::cout << "\nRemoving item " << items[front] << " from the front";
 n--;
 return items[front];
 }
}
template <class T>
T PQueue<T>::first(int& underflow) const
{
 if (empty())
 {
 underflow = 1;
 return -1;
 }
 else
 {
 return items[(front + 1) % maxsize];
 }
}
template <class T>
T PQueue<T>::last(int& underflow) const
{
 if (empty())
 {
 underflow = 1;
 return -1;
 }
 else
 {
 return items[rear];
 }
}
template <class T>
int PQueue<T>::size() const
{
 return n;
}
template <class T>
bool PQueue<T>::empty() const
{
 if (front == rear)
 return true;
 else
 return false;
}
template <class T>
void PQueue<T>::print() const
{
 std::cout << "\nQueue items : ";
 for (int i = (front + 1) % maxsize; i != (rear+1)%maxsize; i=(++i)%maxsize)
 {
 std::cout << "items[" << i << "] = " << items[i] << "\t";
 }
}
template <class T>
void PQueue<T>::increment(int& i)
{
 ++i;
 i %= maxsize;
}
template <class T>
void PQueue<T>::decrement(int& i)
{
 --i;
 i += maxsize; i %= maxsize;
}
#endif // !PriorityQueue_H

Code

#ifndef PQueue_H
#define PQueue_H
#include <cmath>
#include <iostream>
const int maxsize = 5;
template <class T>
class PQueue
{
 T items[maxsize];
 int front, rear,n;
public:
 PQueue(T val);
 PQueue(const PQueue<T>& q);
 ~PQueue();
 void insert(T x, int& overflow);
 int search_position(T x);
 T remove(int& underflow);
 T first(int& underflow) const;
 T last(int& underflow) const;
 int size() const;
 bool empty() const;
 void print () const;
 void increment(int& i);
 void decrement(int& i);
};
template <class T>
PQueue<T>::PQueue(T val)
{
 for (int i = 0; i < maxsize; i++)
 items[i] = val;
 front = rear = maxsize - 1;
 n = 0;
}
template <class T>
PQueue<T>::PQueue(const PQueue<T>& q)
{
 for (int i = 0; i < q.n; i++)
 {
 items[i] = q.items[i];
 }
 front = rear = maxsize - 1;
 n = 0;
}
template <class T>
PQueue<T>::~PQueue() {};
template <class T>
int PQueue<T>::search_position(T x)
{
 int low = front, high = rear;
 int i;
 if (empty()) {
 return (rear+1)%maxsize;
 }
 
 for (i = (front+1)%maxsize; i != (rear+1)%maxsize; increment(i))
 { 
 if (items[i] > x)
 break;
 }
 return i;
}
template <class T>
void PQueue<T>::insert(T x, int& overflow)
{
 overflow = 0;
 if ((rear + 1) % maxsize == front)
 {
 overflow = 1;
 return;
 }
 else
 {
 int index = search_position(x);
 std::cout << "\nInserting item " << x << " at position " << index;
 increment(rear);
 //If index matches the updated value of rear,
 //there must be nothing to shift.
 if(index!=rear)
 {
 int i = rear - 1, j = rear;
 i += maxsize; i %= maxsize;
 j += maxsize; j %= maxsize;
 do
 {
 //Shift all elements 1 position to 
 //the right in item[index...rear]
 items[j] = items[i];
 std::cout << "\nShifting item " << items[i] << " from index "
 << i << " to " << j;
 decrement(i); 
 decrement(j);
 } while (j != index);
 }
 n++;
 items[index] = x;
 }
}
template <class T>
T PQueue<T>::remove(int& underflow)
{
 underflow = 0;
 if (empty())
 {
 underflow = 1;
 return -1;
 }
 else
 {
 increment(front);
 std::cout << "\nRemoving item " << items[front] << " from the front";
 n--;
 return items[front];
 }
}
template <class T>
T PQueue<T>::first(int& underflow) const
{
 if (empty())
 {
 underflow = 1;
 return -1;
 }
 else
 {
 return items[(front + 1) % maxsize];
 }
}
template <class T>
T PQueue<T>::last(int& underflow) const
{
 if (empty())
 {
 underflow = 1;
 return -1;
 }
 else
 {
 return items[rear];
 }
}
template <class T>
int PQueue<T>::size() const
{
 return n;
}
template <class T>
bool PQueue<T>::empty() const
{
 if (front == rear)
 return true;
 else
 return false;
}
template <class T>
void PQueue<T>::print() const
{
 std::cout << "\nQueue items : ";
 for (int i = (front + 1) % maxsize; i != (rear+1)%maxsize; i=(++i)%maxsize)
 {
 std::cout << "items[" << i << "] = " << items[i] << "\t";
 }
}
template <class T>
void PQueue<T>::increment(int& i)
{
 ++i;
 i %= maxsize;
}
template <class T>
void PQueue<T>::decrement(int& i)
{
 --i;
 i += maxsize; i %= maxsize;
}
#endif // !PriorityQueue_H

I am learning about stacks, queues, lists & hash tables from the book Data Structures using C and C++ by Tenenbaum. I am also spending time to take in OOPs essentials, to ensure they sink in well, so that I don't learn by osmosis/need-be basis in the future, and there are no knowledge gaps.

I am learning about stacks, queues, lists & hash tables from the book Data Structures using C and C++ by Tanenbaum. I am also spending time to take in OOPs essentials, to ensure they sink in well, so that I don't learn by osmosis/need-be basis in the future, and there are no knowledge gaps.