Question

我在课堂上学习C ++。他们让我们在Ubuntu的虚拟机上使用Geany。我想念IDE的功能，所以我尝试了几个：Netbeans，Eclipse和Code :: Blocks。

我为家庭作业编写的代码在VM上的Geany中编译和运行没有问题。当我尝试所有其他IDE时，编译器给我一个错误。我在同一个虚拟机上尝试了Windows 7和Ununtu上的Netbeans和Eclipse。在寻找答案时，this help topic说Geany为我做了很多幕后工作。所以我尝试删除我对头文件和源代码的各种#include语句，并且~~解决了问题~~（开玩笑！）并且无法弄清楚到底发生了什么

ArrayBagTester2.cxx :(这是我在Geany中编译/运行的内容）

#include <iostream>
#include <string>
#include "ArrayBag.h"

using namespace std;

int main()
    {
        // a bunch of stuff
    }

ArrayBag.h :(由教授提供，不做任何修改/需要）

#ifndef _ARRAY_BAG
#define _ARRAY_BAG

#include "BagInterface.h"
template<class ItemType>
class ArrayBag : public BagInterface<ItemType>
{
    private:
        static const int DEFAULT_CAPACITY = 4;
        ItemType* itemArray; //array must be dynamic; so pointers are very yes
        int numberOfItems;
        int myCapacity; //added variable to track capacity

    public:
        ArrayBag(int capacity = DEFAULT_CAPACITY); // new constructor
        ArrayBag(const ArrayBag& anotherBag); // copy constructor
        ~ArrayBag(); //destructor
        int getCurrentSize() const;
        int getCapacity() const;
        void resize(int newCapacity); // resize
        bool isEmpty() const;
        bool isFull() const;
        bool add(const ItemType& newEntry);
        bool remove(const ItemType& anEntry);
        void clear();
        bool contains(const ItemType& anEntry) const;
        int getFrequencyOf(const ItemType& anEntry) const;
        vector<ItemType> toVector() const;
        ArrayBag& operator=(const ArrayBag& anotherBag);
};

#include "ArrayBag.cxx"
#endif

BagInterface.h（由教科书作者提供，注意版权。我已经瘫痪以保持其版权。）

//  Created by Frank M. Carrano and Tim Henry.
//  Copyright (c) 2013 __Pearson Education__. All rights reserved.

/** Listing 1-1.
    @file BagInterface.h */
#ifndef _BAG_INTERFACE
#define _BAG_INTERFACE

#include <vector>
using namespace std;

template<class ItemType>
class BagInterface
{
public:
   virtual .... stuff here, all virtual functions ...
};
#endif

ArrayBag.cxx：肉和土豆以及我们应该（仅）编辑的内容，错误从第9行开始：

#include <vector>
#include <cstddef>
#include <algorithm>

#include "ArrayBag.h"

// Constructor; creates and initializes an empty Bag of "capacity" size
template <class ItemType>
********************//LINE 9:**************************
ArrayBag<ItemType>::ArrayBag(int capacity)
{
    myCapacity = capacity;
    itemArray = new ItemType[myCapacity];
    numberOfItems = 0;
}

// Copy constructor; creates and initializes Bag from another Bag
template <class ItemType>
ArrayBag<ItemType>::ArrayBag(const ArrayBag& anotherBag)
{
    numberOfItems = anotherBag.getCurrentSize();
    myCapacity = anotherBag.getCapacity();
    itemArray = new ItemType[myCapacity];

    for (int i = 0; i < numberOfItems; ++i)
        itemArray[i] = anotherBag.itemArray[i];
}

//destructor
template <class ItemType>
ArrayBag<ItemType>::~ArrayBag()
{
    delete [] itemArray;
}

// Assignment operator
template <class ItemType>
ArrayBag<ItemType>& ArrayBag<ItemType>::operator=(const ArrayBag<ItemType>& anotherBag)
{
    // see if we're trying to assign to ourself, stupid user
    if (&anotherBag == this)
        return *this;
    clear();
    //ArrayBag<ItemType>::~ArrayBag();
    delete [] itemArray;
    //ArrayBag<ItemType>::ArrayBag(anotherBag);
    numberOfItems = anotherBag.getCurrentSize();
    myCapacity = anotherBag.getCapacity();
    itemArray = new ItemType[myCapacity];

    for (int i = 0; i < numberOfItems; ++i)
        itemArray[i] = anotherBag.itemArray[i];

    return *this;
}

// Return the number of Items being stored in the Bag
template <class ItemType>
int ArrayBag<ItemType>::getCurrentSize() const
{
    return numberOfItems;
}

// Return the capacity of the bag (the maximum Items it can store)
template <class ItemType>
int ArrayBag<ItemType>::getCapacity( ) const
{
    return myCapacity;
}

//Resizes the bag's capacity to newCapacity
//if the new size is larger, copy all bag contents
// we don't downsize a bag in HW2
template <class ItemType>
void ArrayBag<ItemType>::resize(int newCapacity)
{
    ItemType* oldArray = itemArray;
    itemArray = new ItemType[newCapacity];
    for(int i = 0; i < myCapacity; ++i)
        itemArray[i] = oldArray[i];
    delete [] oldArray;
}

// Report whether the Bag is empty
// Return true if the Bag is empty (storing no Items);
// Return false if Items exist in the Bag
template <class ItemType>
bool ArrayBag<ItemType>::isEmpty() const
{
    return (numberOfItems == 0);
}

// Report whether the Bag is full
// Return true if the Bag is filled to capacity
// Return false if there is still room
template <class ItemType>
bool ArrayBag<ItemType>::isFull() const
{
    //This bag is resizeable, so it's never full
    return false;
}

// Give the Bag a new Item to store
// If Bag is full, double capacity and add newItem
// Else, Bag must add this Item to its Item array and update its numberOfItems
// If Bag is full after this, return true; else return false
template <class ItemType>
bool ArrayBag<ItemType>::add(const ItemType& newItem)
{
    if (numberOfItems == myCapacity)
    {
        resize(myCapacity * 2);
        myCapacity = myCapacity * 2;
    }

    itemArray[numberOfItems++] = newItem;

    //This bag is resizeable, so it's never full
    return false;
}

// Make the Bag act like an empty Bag again
template <class ItemType>
void ArrayBag<ItemType>::clear()
{
    numberOfItems = 0;
}

// Remove an Item from the bag
// If Item is not there, nothing changes and we return false
// Else, we fill in its spot in that Item array and count number of Items down
template <class ItemType>
bool ArrayBag<ItemType>::remove(const ItemType& anItem)
{
    for (int i = 0; i < numberOfItems; ++i)
    {
        if (itemArray[i] == anItem)
        {
            itemArray[i] = itemArray[--numberOfItems];
            return true;
        }
    }
    return false;
}

// Check if an Item is in the Bag
// Return true if it is in the Bag, and false if not
template <class ItemType>
bool ArrayBag<ItemType>::contains(const ItemType& anItem) const
{
    for (int i = 0; i < numberOfItems; ++i)
        if (itemArray[i] == anItem) return true;
    return false;
}

// Check how many times an Item is in the Bag
// return 0 if it's not there; otherwise,
// return the number of times it occurs
template <class ItemType>
int ArrayBag<ItemType>::getFrequencyOf(const ItemType& anItem) const
{
    int frequency = 0;

    for (int i = 0; i < numberOfItems; ++i)
        if (anItem == itemArray[i]) ++frequency;

    return frequency;
}

// Make an output vector of Items from the bag (for checking)
template <class ItemType>
vector<ItemType> ArrayBag<ItemType>::toVector() const
{
    vector<ItemType> bagContents;

    for (int i = 0; i < numberOfItems; ++i)
        bagContents.push_back(itemArray[i]);

    return bagContents;
}

以下是为ArrayBag.cxx中的每个方法生成的错误：

C：\ Users ... \ HW2 \ ArrayBag.cxx | 9 |错误：重新定义   'ArrayBag :: ArrayBag（INT）' |   C：\用户\ HW2 \ ArrayBag.cxx | 9 |错误：   先前在此声明的'ArrayBag :: ArrayBag（int）'

......为了清晰起见而截断...

我想了解：

为什么Geany会在其他人不工作的时候工作？真正让makefile变得神奇的是什么？
在Windows上是否有（简单的）修复到Netbeans（而不是Netbeans导致问题）来解决这个问题？（我似乎更喜欢Netbeans，没有其他原因。）或：
什么是传统或标准包含这些关系和文件的方式？

Answer 1

包含文件ArrayBag.cxx（这是非常奇怪的方式，但无论如何）并不打算编译。只需编译ArrayBagTester2.cxx即可。

顺便说一句：我同意先前的评论，即这件事是怪异的......

Answer 2

您不应该将ArrayBag.cxx编译为单独的编译单元。见这里：

Why can templates only be implemented in the header file?

模板实现文件不是单独的编译单元，但是您的命令行建议它被编译为一个。

C ++编译＆amp;在Geany中运行，而不是在Netbeans，Eclipse，Code :: Blocks中运行。为什么？

2 个答案: