小编Jon*_*tai的帖子

在我的程序中，我需要创建一个大型 3d 数组（~1GB），我当前使用两个 for 循环来初始化数组：

float*** array = new float** [m_width];

for (unsigned int i = 0; i < m_width; i++)
{
    array3d[i] = new float * [m_height];
    for (unsigned int j = 0; j < m_height; j++)
    {
        array3d[i][j] = new float[m_layers];
    }
}

该代码工作正常，但速度非常慢。所以我的问题是：是否有更快的方法来初始化/保留多维数组的内存？（几乎可以立即创建一维数组）

I have definded the following class witch creates and frees an opaque object (e.g. an operating system handle)

class A
{
public:

    A(...)
    {
        allocateHandle(&h);
    }

    ~A()
    {
        freeHandle(h);
    }

    SomeHandle h;
}

When creating and resizing std::vector of A, the program crashes.

std::vector<A> vec;
vec.reserve(2);

vec.emplace_back(...);
vec.emplace_back(...);
vec.emplace_back(...); //crash

When std::vector reallocates memory, it calls the move constructor on all the objects, thus also moving the handle in A (which is basically an integer).

However, it also calls the …