添加到动态数组 [英] Adding to dynamic array

问题描述

免责声明：是的，我知道std :: vector。我这样做是为了学习。

Disclaimer: Yes, I know about std::vector. I'm doing this for the sake of learning.

我正在制作一个动态数组类，并且正在尝试增加工作量。

I'm working on making a dynamic array class, and I'm trying to get add to work.

template <class T>
void Array<T>::add(T value)
{
    T * tmp = new T[mCount];

    for (int i = 0; i < mCount; i++)
    {
        tmp[i] = mData[i];
    }

    mCount++;

    delete[] mData;
    mData = tmp;

    mData[mCount - 1] = value;
}

它的工作原理是……该函数可用于添加元素，但是退出时程序会崩溃。没有错误，什么都没有。它只是冻结，我必须使用（Shift + F5）将其关闭。

It works... sort of. The function works in adding the element, but then the program crashes when exiting. No errors, no nothing. It just freezes, and I have to close it using (Shift + F5).

那么，这怎么了？

这是我的全班。如果我不包含函数，则表示函数中没有代码。

Here's my whole class. If I didn't include a function it means there's no code in it.

#ifndef ARRAY_H
#define ARRAY_H

using namespace std;

template <class T>
class Array
{
private:
    T * mData;
    int mCount;

public:
    Array();
    ~Array();

    void add(T value);
    void insert(T value, int index);
    bool isEmpty();
    void display();
    bool remove(T value);
    bool removeAt(int index);
    int size();

    T & operator[](const int index);
};

// Constructors / Destructors
// --------------------------------------------------------

template <class T>
Array<T>::Array()
{
    mCount = 0;
    mData = new T[mCount];
    for (int i = 0; i < mCount; i++)
        mData[i] = 0;
}

template <class T>
Array<T>::~Array()
{
    delete[] mData;
}

// General Operations
// --------------------------------------------------------

template <class T>
void Array<T>::add(T value)
{
    T * tmp = new T[mCount];

    for (int i = 0; i < mCount; i++)
    {
        tmp[i] = mData[i];
    }

    mCount++;

    delete[] mData;
    mData = tmp;

    mData[mCount - 1] = value;
}

template <class T>
void Array<T>::display()
{
    if (isEmpty())
    {
        cout 
            << "The array is empty."
            << "\n\n";
        return;
    }

    cout << "(";

    for (int i = 0; i < mCount; i++)
    {

        cout << mData[i];

        if (i < mCount - 1)
            cout << ", ";
    }

    cout << ")" << "\n\n";
}

template <class T>
bool Array<T>::isEmpty()
{
    return mCount == 0;
}

template <class T>
int Array<T>::size()
{
    return mCount;
}

// Operator Overloads
// --------------------------------------------------------

template <class T>
T & Array<T>::operator[](const int index)
{
    return mData[index];
}

#endif

如果您需要任何其他信息

If you need any additional info lemme know and I can post it.

推荐答案

假设 mCount 保持数组中的元素数量，然后添加一个新元素时，您实际上必须分配至少 mCount + 1 个元素（假设您当然希望保留所有旧元素，新的）：

Assuming mCount keeps the number of elements in the array, then when adding a new element you really have to allocate at least mCount + 1 elements (assuming of course you want to keep all the old ones and the new one) via:

T * tmp = new T[mCount + 1];

相对于：

T * tmp = new T[mCount];

如果除教育目的外，还请使用 std ::向量。例如，您的 add 函数不是异常安全的。

If it's for anything else other than educational purposes, please use std::vector instead. For example your add function is not exception safe.

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