这款便携式，符合标准，优雅吗？ [英] is this portable, conforming to standard, elegant?
问题描述
class vector3
{
public：
union
{
float [3]数据;
struct
{
浮动x，y，z;
};
};
};
带数据数组的
访问方便文件io和x，y，z用于其他东西
" rz" < gk *** @ hjkjhk.plwrote in news：eq ********** @ nemesis.news.tpi.pl:
class vector3
{
public：
union
{
float [3]数据;
struct
{
浮动x，y，z;
};
};
};
带数据数组的
访问方便文件io和x，y，z用于其他
items
结构是否可能以不同的方式进行字节打包
而不是数组？
RZ写道：
class vector3
{
public：
union
{
float [3]数据;
语法错误。
浮点数据[3];
struct
{
浮动x，y，z;
} ;
};
};
带数据数组的
访问方便文件io和x，y，z用于其他东西
取决于你如何使用它。仅当您访问上次修改的联合的
相同成员时，才会定义行为。换句话说，如果你用
写入x，并尝试用数据[0]读取它，你得到UB。
是吗可能是结构可能以不同的方式进行字节打包
比数组？
您是否询问data []是否始终按此顺序包含值x，y，z？
（如结构中所示）那么答案是肯定的。
class vector3
{
public:
union
{
float[3] data;
struct
{
float x, y, z;
};
};
};
access with data array is convenient for file io and x,y,z for other things
"r.z." <gk***@hjkjhk.plwrote in news:eq**********@nemesis.news.tpi.pl:
class vector3
{
public:
union
{
float[3] data;
struct
{
float x, y, z;
};
};
};
access with data array is convenient for file io and x,y,z for other
things
Is it possible that the structure may be byte-packed in a different manner
than an array?
r.z. wrote:class vector3
{
public:
union
{
float[3] data;syntax error.
float data[3];struct
{
float x, y, z;
};
};
};
access with data array is convenient for file io and x,y,z for other things
Depends on how you use it. Behavior is only defined if you access the
same member of the union that you last modified. In other words, if you
write to x, and try to read it with data[0], you get UB.
Is it possible that the structure may be byte-packed in a different mannerthan an array?do you ask whether data[] will always contain values x, y, z in this order?
(like in the structure) then the answer is yes.
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