c++ - 关于 union 的疑惑

Question

class FMatrix
{
public:
    union
    {
        MS_ALIGN(16) float M[4][4] GCC_ALIGN(16);
    };
//...
}

定义一个 4X4 的浮点数组，为什么要用 union 包裹起来呢？这样做有什么好处？

Answer 1

I just want to set align for M alone, there is no other use.