我刚刚完成了这个程序的工作，但从一开始我注意到它不知何故打印出它应该的一切。 需要首先从顶部开始打印堆栈中的整数，然后从底部开始再次执行。 它正确打印从上到下，但由于某种原因，它只打印从底部到顶部的最底部数字。 例如，如果堆栈包含整数1,2,3,4,5,6， 其中1位于堆栈的底部，6位于顶部。 该程序应打印以下内容： 顶部{6 5 4 3 2 1}底部底部{1 2 3 4 5 6}顶部
但它会打印以下内容： 顶部{6 5 4 3 2 1}底部{1}顶部
这是打印功能：
void Print() const
// Prints stack contents to stdout in both top-to-bottom and bottom-to-top order
{
Node* temp = topPtr;
cout << "Top { ";
// Forward print
while (temp != NULL)
{
cout << temp->data << " ";
if (temp->next == NULL)
break;
temp = temp->next;
}
cout << "} Bottom Bottom { ";
// Reverse print
while (temp != NULL)
{
cout << temp->data << " ";
temp = temp->previous;
}
cout << "} Top" << endl;
} // End Print()
}; //结束类堆栈
如果你需要任何进一步的参考，那么是main（）
#include <iostream>
#include <fstream>
#include <new>
#include <cstddef>
#include "stack.h"
using namespace std;
int main(int argc, char* argv[])
{
ifstream inputs; // Input file for commands
char op; // Hold operation and optional char input
int value; // Value input from file
string comment; // Holds comment from file
Stack* sPtr = NULL; // Will point to stack object
// Output usage message if one input file name is not provided
if (argc != 2)
{
cout << "Usage:\n project03 <inputfile>\n";
return 1;
}
// Attempt to open input file -- terminate if file does not open
inputs.open(argv[1]);
if (!inputs)
{
cout << "Error - unable to open input file" << endl;
return 1;
}
// Input and echo header comment from file
getline(inputs, comment); // Input and echo the comment appearing in the test file
cout << endl << '#' << comment << endl;
// Process commands from input file
inputs >> op; // Attempt to input first command
while (inputs)
{
switch (op) // Process operation input from file
{
case '#': // Test file comment
getline(inputs, comment); // Input and echo the comment appearing in the test file
cout << '#' << comment << endl;
break;
case 'c': // Constructor
cout << endl << "Stack( )";
try
{
sPtr = new Stack( ); // Attempt to create an empty stack object
cout << " -- Successful" << endl;
}
catch ( std::bad_alloc )
{
cout << "Failed : Terminating now..." << endl;
return 1;
}
break;
case '+': // Push
inputs >> value;
cout << "Push(" << value << ")";
try
{
sPtr->Push(value);
cout << " -- successful";
}
catch (StackFull)
{
cout << " -- Failed Full Stack";
}
cout << endl;
break;
case '-': // Pop
cout << "Pop() -- ";
try
{
sPtr->Pop();
cout << "successful";
}
catch (StackEmpty)
{
cout << "Failed Empty Stack";
}
cout << endl;
break;
case 'f': // IsFull
cout << "IsFull() -- ";
try
{
if (sPtr->IsFull())
cout << "true";
else
cout << "false";
}
catch ( ... )
{
cout << "operation failed";
}
cout << endl;
break;
case 'e': // IsEmpty
cout << "IsEmpty() -- ";
try
{
if (sPtr->IsEmpty())
cout << "true";
else
cout << "false";
}
catch ( ... )
{
cout << "operation failed";
}
cout << endl;
break;
case 'm': // Make Empty
sPtr->MakeEmpty();
cout << "MakeEmpty()" << endl;
break;
case 'p': // Print Stack
cout << "Print() -- ";
sPtr->Print();
break;
case 't': // Top of Stack
try
{
cout << "Top() -- " << sPtr->Top() << endl;
}
catch (StackEmpty)
{
cout << "Top() -- Failed Empty Stack" << endl;
}
break;
case '>': // Max value within Stack
try
{
cout << "Max() -- " << sPtr->Max() << endl;
}
catch (StackEmpty)
{
cout << "Max() -- Failed Empty Stack" << endl;
}
break;
case '<': // Min value within Stack
try
{
cout << "Min() -- " << sPtr->Min() << endl;
}
catch (StackEmpty)
{
cout << "Min() -- Failed Empty Stack" << endl;
}
break;
case '?': // Peek(n) Stack
inputs >> value;
try
{
cout << "Peek(" << value << ") -- " << sPtr->Peek(value) << endl;
}
catch (StackInvalidPeek)
{
cout << "Peek(" << value << ") -- Failed Invalid Peek" << endl;
}
break;
case 's': // Size of Stack
cout << "Size() -- " << sPtr->Size() << endl;
break;
case 'd': // Destructor
delete sPtr;
sPtr = NULL;
cout << "~Stack()" << endl << endl;
break;
default: // Error
cout << "Error - unrecognized operation '" << op << "'" << endl;
cout << "Terminating now..." << endl;
return 1;
break;
}
inputs >> op; // Attempt to input next command
}
return 0;
} // End main()
这里是stack.cpp（stack.h）的头文件
//
// stack.h
//
// Specification file for Stack class, a stack of integers implemented
// using doubly-linked nodes.
//
// ***** DO NOT MODIFY THIS FILE *****
//
#include <iostream>
using namespace std;
#ifndef STACK_H
#define STACK_H
class StackEmpty { /* No Code */ };
// StackEmpty exception class - throw an object of this type when stack is empty
// Hint: there is no code for exception classes
class StackFull { /* No Code */ };
// StackFull exception class - throw an object of this type when stack is full
class StackInvalidPeek { /* No Code */ };
// StackInvalidPeek exception class - throw an object of this type when invalid peek position is used
struct Node // Node data type for storing a single stack entry along with pointers to
{ // neighboring entries (previous and next) in the stack
Node* previous; // Member variable that holds the address of the predessor node in the stack sequence
Node* next; // Member variable that holds the address of the successor node in the stack sequence
int data; // Member variable that holds the data value
};
class Stack // Implements stack of integers ADT using doubly-linked sequence of nodes
{
private:
Node* topPtr; // Points to the top node on the stack array
public:
Stack(); // Default constructor initializes empty stack
~Stack(); // Destructor deallocates all nodes from stack
// Must not create a memory leak
void Push(int n); // Pushes integer n onto top of stack.
// If unable to push, throws StackFull exception.
void Pop(); // Removes top integer from stack
// If stack is already empty, throws StackEmpty exception
bool IsEmpty() const; // Returns true if stack is empty; false otherwise
bool IsFull() const; // Returns true if stack is full; false otherwise
void MakeEmpty(); // Removes all nodes from stack leaving an empty, but usable stack
// Must not create a memory leak
int Top() const; // Returns value of top integer on stack WITHOUT modifying the stack
// If stack is empty, throws StackEmpty exception
int Size() const; // Returns number of items on stack WITHOUT modifying the stack
int Max() const; // Returns value of largest integer within stack WITHOUT modifying the stack
// If stack is empty, throws StackEmpty
int Min() const; // Returns value of smallest integer within stack WITHOUT modifying the stack
// If stack is empty, throws StackEmpty
int Peek( int n) const; // Returns stack value n levels down from top of stack. Peek(0) = Top()
// If position n does not exist, throws StackInvalidPeek
. ./******* DO NOT MODIFY ANY OF THE CODE FOR PRINT() *******/
/****** DO NOT PLACE A COPY OF PRINT() CODE IN STACK.CPP!!! *******/
void Print() const
// Prints stack contents to stdout in both top-to-bottom and bottom-to-top order
{
Node* temp = topPtr;
cout << "Top { ";
// Forward print
while (temp != NULL)
{
cout << temp->data << " ";
if (temp->next == NULL)
break;
temp = temp->next;
}
cout << "} Bottom Bottom { ";
// Reverse print
while (temp != NULL)
{
cout << temp->data << " ";
temp = temp->previous;
}
cout << "} Top" << endl;
} // End Print()
}; // End Class Stack
#endif
最后这里是stack.cpp，这是我创建的文件，其余的是给出的。
//
// stack.cpp
//
//
// Created by Otapia on 9/19/11.
// Copyright 2011 __MyCompanyName__. All rights reserved.
//
#include <iostream>
#include <new>
#include "stack.h"
Stack::Stack() // Default constructor initializes empty stack
{
topPtr = NULL;
}
Stack::~Stack() // Destructor deallocates all nodes from stack
// Must not create a memory leak
{
Node* tempPtr;
while ( topPtr != NULL )
{
tempPtr = topPtr;
topPtr = topPtr->next;
delete tempPtr;
}
}
void Stack::Push(int n) // Pushes integer n onto top of stack.
// If unable to push, throws StackFull exception.
{
if(!IsFull())
{
Node* tempPtr = new Node;
tempPtr->data = n;
tempPtr->next = topPtr;
topPtr = tempPtr;
}
else
throw IsFull();
}
void Stack::Pop() // Removes top integer from stack
// If stack is already empty, throws StackEmpty exception
{
if (!IsEmpty())
{
Node* tempPtr;
tempPtr = topPtr;
topPtr = topPtr->next;
delete tempPtr;
}
else
throw StackEmpty();
}
bool Stack::IsEmpty() const // Returns true if stack is empty; false otherwise
{
return(topPtr == NULL);
}
bool Stack::IsFull() const // Returns true if stack is full; false otherwise
{
Node* location;
try
{
location = new Node;
delete location;
return false;
}
catch(std::bad_alloc)
{return true; }
}
void Stack::MakeEmpty() // Removes all nodes from stack leaving an empty, but usable stack
// Must not create memory leak
{
Node* tempPtr;
while ( topPtr != NULL ) {
tempPtr = topPtr;
topPtr = topPtr->next;
delete tempPtr;
}
topPtr = NULL;
}
int Stack::Top() const // Returns value of top integer on stack WITHOUT modifying the stack
{
if(!IsEmpty())
return topPtr->data;
throw StackEmpty();
}
int Stack::Size() const // Returns number of items on stack WITHOUT modifying the stack
{
Node* temp = topPtr;
int count = 0;
while (temp != NULL)
{
temp = temp->next;
count ++;
}
return count;
}
int Stack::Max() const // Returns value of largest integer within stack WITHOUT modifying the stack
// If stack is empty, throws StackEmpty
{
int max = 0;
int n;
Node* temp = topPtr;
if(!IsEmpty())
{
while(temp != NULL)
{
n = temp->data;
if(n > max)
{
max = n;
}
temp = temp->next;
}
return max;}
else
throw StackEmpty();
}
int Stack::Min() const // Returns value of smallest integer within stack WITHOUT modifying the stack
// If stack is empty, throws StackEmpty
{int min = 100;
int n;
Node* temp = topPtr;
if(!IsEmpty())
{
while(temp != NULL)
{
n = temp->data;
if(n < min)
{
min = n;
}
temp = temp->next;
}
return min;}
else
throw StackEmpty();
}
int Stack::Peek(int n) const // Returns stack value n levels down from top of stack. Peek(0) = Top()
// If position n does not exist, throws StackInvalidPeek
{
int num = 0;
int x = 0;
Node* temp = topPtr;
if(!IsEmpty())
{
while(temp != NULL)
{
if (x >= n || temp->next == NULL)
break;
temp = temp->next;
x++;
}
if (n <= x)
{
num = temp->data;
}
else throw StackInvalidPeek();
}
else
throw StackInvalidPeek();
return num;
}
答案 0 :(得分：1)
简单。
while (temp != NULL)
{
cout << temp->data << " ";
temp = temp->previous;
}
从您的问题描述和错误代码中，我认为temp->previous不正确。我假设这是在某种push函数中设置的。
void Stack::Push(int n) // Pushes integer n onto top of stack.
// If unable to push, throws StackFull exception.
{
if(!IsFull())
{
Node* tempPtr = new Node;
tempPtr->data = n;
tempPtr->next = topPtr;
topPtr = tempPtr;
} else
throw IsFull();
}
你永远不会设置previous，因此它会留下一些未指定的值（零）。此外，您的cpp文件中未设置或检查任何位置 previous。它应该在这里设置，虽然实际上不需要在其他任何地方。
最后，throw IsFull()是一个例外。您可能并不是指throw函数调用的bool结果。