将ccyle数组视为std :: array [英] Treat C cstyle array as std::array

问题描述

有没有任何安全和标准的兼容方式来将一个C样式数组作为std ::数组，而不将数据复制到一个新的std ::数组？

Is there any safe and standard compliant way to treat a C style array as an std::array without copying the data into a new std::array?

这显然不编译，但是我想要的效果（我真正的使用是更复杂，但这个简短的示例应该显示我想做的）。我想reinterpret_cast将工作，但可能不安全？

This clearly doesn't compile, but is the effect I would like (my real use is more complicated but this short sample should show what I'd like to do). I guess a reinterpret_cast would "work" but probably isn't safe?

#include <array>

int main()
{
    int data[] = {1, 2, 3, 4, 5};

    // This next line is the important one, treating an existing array as a std::array
    std::array<int, 5>& a = data;
}

感觉应该是可能的，因为数据应该存储相同。

It feels like it ought to be possible as the data should be stored identically.

编辑：要清楚我不想清除一个新的std ::数组，我想引用现有的数据一个。

edit: To be clear I don't want to clear a new std::array, I want to refer to the existing data as one.

推荐答案

你不能这样做。 std :: array 是一个聚合并保存它自己的数据块（相对于一个可以轻松重新分配的数据块的指针）。所以没有办法避免所有元素的副本。在C ++ 11中，这是特别重要的，因为数组的数据不能被移动，所以没有有效的 std :: swap 函数。

You cannot do that. The std::array is an aggregate and holds its own block of data (as opposed to a pointer to a block of data that can be easily reassigned). So there's no way of avoiding a copy of all the elements. In C++11 this is particularly important because the array's data cannot be moved, so there's no efficient std::swap function, for example.

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