Example 7

#include <iostream>
#include <stdexcept>
#include <vector>

template <typename T>
class Queue{
     private:
         std::vector<T> elements;
         
     public:
         Queue(){}//default constructor
         T back(){ // return last element
             return elements.back();
         }
         void push(const T& element){//add an element
              elements.push_back(element);
         }
         void pop(){//erase first element
             if (elements.empty()) {
                 throw std::out_of_range("Stack<>::pop(): empty stack");
             }
             elements.erase( elements.begin() );
         }
         bool empty(){return elements.empty();}
         int size(){return elements.size();
         }
         T front(){
             if (elements.empty()) {
                 throw std::out_of_range("Stack<>::pop(): empty stack");
             }
             return elements.front();}
};
         
template< class T >
//Note that we are passing by reference, so original queue will be erased
void iterate_Queue(Queue<T>& queue){
     while(not queue.empty()) {
         std::cout << "(" << queue.front()<< ", " << queue.back() << ")";
         std::cout << "with size:"<< queue.size() << std::endl;
         queue.pop();
     }
     std::cout << std::endl;
}
typedef Queue<int> intQueue;// It's common to define typedef's in order to simply 
//definicions
//typedef Queue< intQueue > queue_intQueue;
typedef Queue< Queue<int> > queue_intQueue;
                       // ^-- This space isn't opcional, copiler'd think that is a << operador
int main() {
     try{
         intQueue y;
         y.push(1);
         y.push(2);
         y.push(3);
         y.push(4);
         iterate_Queue(y);

         y.push(15);
         iterate_Queue(y);

         y.front();//exception, queue is empty
     } catch (const std::exception& ex) {
         std::cerr << "Exception: " << ex.what() << std::endl;
     } 
     
     return 0;
}

output:

(1, 4)with size:4
(2, 4)with size:3
(3, 4)with size:2
(4, 4)with size:1

(15, 15)with size:1

Exception: Stack<>::pop(): empty stack

RUN SUCCESSFUL (total time: 244ms)




read more -->