如何在C ++中打印堆栈

Question

so for an assignment of mine we have to modify a stack class and test it. I have successfully added all the necessary methods, but what I am stuck on is how best to print out what is in the stack when I demonstrate it. So basically, I'm going to fill the stack with random data and test the various methods I implemented, but I don't know how to print out the stack to the console to show that I've actually done what I'm supposed. I know this is a pretty basic question, but I'm just stuck here. I am guessing I have to use the method getTop somehow, but how to I use that to print what's in the stack. Here are all my files:

StackP.cpp

    #include <cassert>

    using namespace std;

     #include "StackP.h"

     Stack::Stack()
        : topPtr(0) {
     }

     Stack::Stack(const Stack& aStack)
        throw(OutOfStorageException) {

        // Original list is empty
        if (aStack.topPtr == 0) {
           topPtr = 0;
        }
        else {
           try {
              // Copy first node
              topPtr = new StackNode;
              topPtr->item = aStack.topPtr->item;

              // Copy rest of list
              StackNode* newPtr = topPtr;    // Pointer to new list 
              for (StackNode* origPtr = aStack.topPtr->next;
                   origPtr != 0;
                   origPtr = origPtr->next) {
                 newPtr->next = new StackNode;
                 newPtr = newPtr->next;
                 newPtr->item = origPtr->item;
              }

             newPtr->next = 0;
           }
           catch (const bad_alloc&) {
           // Release all memory successfully allocated in this copy
              while (!isEmpty() ) {
                pop();
              }
              throw OutOfStorageException("Out of memory");
           }
        }
     }

     Stack::~Stack() {

        // Pop until stack is empty
    while (!isEmpty() ) {                            
       pop();
    }
    assert(topPtr == 0);
 }

 bool Stack::isEmpty() const {

    return topPtr == 0;
 }

 void Stack::push(const StackItemType& newItem)
    throw(OutOfStorageException) {

    try {
       StackNode* newPtr = new StackNode;

       newPtr->item = newItem;

       newPtr->next = topPtr;
       topPtr = newPtr;
    }
    catch (const bad_alloc&) {
       throw OutOfStorageException("Out of memory");
    }
    }
 }

 void Stack::pop()
    throw(OutOfDataException) {

    if (isEmpty() ) {
       throw OutOfDataException("Cannot pop an empty stack.");
    }
    StackNode* temp = topPtr;
    topPtr = topPtr->next;

    temp->next = 0;  // safeguard
    delete temp;
 }

 void Stack::pop(StackItemType& stackTop)
    throw(OutOfDataException) {

    if (isEmpty() ) {
       throw OutOfDataException("Cannot pop an empty stack.");
    }
    stackTop = topPtr->item;
    StackNode* temp = topPtr;
    topPtr = topPtr->next;

    temp->next = 0;  // safeguard
    delete temp;
 }

 void Stack::getTop(StackItemType& stackTop) const
    throw(OutOfDataException) {

    if (isEmpty() ) {
       throw OutOfDataException("Cannot get the top of an empty stack.");
    }
    stackTop = topPtr->item;
 }

  void Stack::popAndDiscard(int count) {

    while (count>0 && !isEmpty()) {

      pop();
      count--;
      }//end while

    }// end popAndDiscard

StackP.h:

#ifndef STACKP_H
 #define STACKP_H 1

 #include "OutOfStorageException.h"
 #include "OutOfDataException.h"

 typedef int StackItemType;

 class Stack {
 public:

    Stack();

    Stack(const Stack& aStack)
       throw(OutOfStorageException);

    ~Stack();

    bool isEmpty() const;

    void push(const StackItemType& newItem)
       throw(OutOfStorageException);

    void pop()
       throw(OutOfDataException);

    void pop(StackItemType& stackTop)
       throw(OutOfDataException);

    void getTop(StackItemType& stackTop) const
       throw(OutOfDataException);

    void popAndDiscard(int count);


 private:

    struct StackNode {
       StackItemType item;

       StackNode* next;
    };

    StackNode* topPtr;
 };

  #endif 

Thanks in advance for your help!

Answer 1

You should add print function as @WhozCraig suggested:

void print(std::ostream& os)
{
    StackNode* current = topPtr;
    while(current != NULL)
    {
        os<<current->item<< " ";
        current = current->next;
    }
}

don't forget to #include <ostream>