C ++中的向量实现

Question

我试图实现Vector的一个函数，即Resize 据我所知，我实现的所有其他功能都很好

在测试代码中，我试图打印出可能发生的每种可能情况，但是当我打印出新Vector的大小时（poitner为整数，称为_elements） 我收到错误＆＃34;＃。exr触发断点 由于我设置在循环中的测试者（主）的一些奇怪的原因＆＃34; i＆lt; 8＆＃34;它工作正常，但如果我做＆lt; =它触发它

我相信这是由调整大小功能引起的，但即使在调试器之后我似乎无法找到问题 （函数的表达式在代码中）

我创造的矢量成功地为那些可能想知道的人提供了智慧

为什么会这样？

具有以下输入/输出的功能是：

Vector::Vector(const Vector& other)
{
    _elements = new int;
    _size = other._size;
    _capacity = other._capacity;
    _resizeFactor = other._resizeFactor;
    for (int i = 0; i < _size; ++i)
    {
        _elements[i] = other._elements[i];
    }

}

//change _size to n, unless n is greater than the vector's capacity
//same as above, if new elements added their value is val
void Vector::resize(int n, const int& val)  
{
    if (n <= _capacity)
    {
        while (n < _size)
        {
            pop_back();
        }

        while (n > _size)
        {
            push_back(val);
        }

        _capacity = n;

    }
    else if (n > _capacity)
    {

        reserve(n);
        while (n > _size)
        {
            push_back(val);

        }
    }
}

//change the  capacity
void Vector::reserve(int n)                 
{

    if (n > _capacity)
    {
        int size = _resizeFactor;
        while (n - _capacity > size)
        {
            size = size + _resizeFactor;
        }
        _capacity += size;
    }
}



//adds element at the end of the vector
void Vector::push_back(const int& val)
{

    if (_size < _capacity)
    {
        _elements[_size] = val;
        _size++;    
    }
    else if (_size == _capacity)
    {
        int* a = new int[_capacity + _resizeFactor];
        for (int i = 0; i < _size; i++)
        {
            a[i] = _elements[i];
        }

        _capacity += _resizeFactor;
        _elements = new int[_capacity];

        for (int i = 0; i < _size; i++)
        {
            _elements[i] = a[i];
        }
        delete a;
        _elements[_size] = val;
        _size++;
    }
}


void Vector::pop_back()         
{
    if (_size > 0)
    {
        _elements[_size] = NULL;
        _size--;
    }
}

我用

检查

void print(const Vector& p)
{

    cout << "Size = " << p.size() << ", Capacity = " << p.capacity() << ",      isEmpty = " << (p.empty() ? "True" : "False") << endl;
}

并在主要：

Vector a(10);
for (int i = 0; i <= 8; i++)
    a.push_back(i+1);
print(a);
a.push_back(10);
print(a);
a.push_back(11);
print(a);
int x = 99;
a.resize(a.capacity() + 11, x);
print(a);