如何使用一维数组列表初始化二维数组?

问题描述

如何使用一维数组列表初始化二维数组?

How can I initialize 2d array with a list of 1d arrays?

void main()
{
    int a[] = { 1,2,3 };
    int b[] = { 4,5,6 };
    int array[][3] = { a,b };
}

推荐答案

C ++中的原始数组属于第二类公民.无法分配它们，也不能复制它们，这意味着您不能使用它们来初始化其他数组，并且它们的名称在大多数情况下会变成指针.

raw arrays in C++ are kind of second class citizens. They can't be assigned and they can't be copied, which means you can't use them to initialize other arrays, and their name decays into a pointer in most circumstances.

Lucky C ++ 11提供了一种解决方案. std::array的作用类似于原始数组，但是没有缺点.您可以改用它们来构建二维数组，例如

Lucky C++11 offers a solution. std::array acts like a raw array, but it doesn't have the drawbacks. You can use those instead to build a 2d array like

std::array<int, 3> foo = {1,2,3};
std::array<int, 3> bar = {3,4,5};
std::array<std::array<int, 3>, 2> baz = {foo, bar};

并且如果您具有C ++ 17支持，则可以利用类模板参数推导摆脱了必须指定模板参数的麻烦，并且代码简化为

and if you have C++17 support you can leverage class template argument deduction to get rid of having to specify the template parameters and the code simplifies to

std::array foo = {1,2,3};
std::array bar = {3,4,5};
std::array baz = {foo, bar};

您可以在此在线示例中找到工作

which you can see working in this live example

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