空结构体的 sizeof 在 C 中为 0，在 C++ 中为 1为什么？
可能的重复：
C++ 中的空类
C 中空结构的大小是多少？< /a>
我在某处读到C++中空结构的大小是1。所以我想到验证它。 不幸的是，我将其保存为 C 文件并使用
这意味着
struct Empty {
};
int main(void)
{
printf("%d",(int)sizeof(Empty));
}
编译为 C 文件时打印 0 ，编译为 C++ 文件时打印 1 。我想知道原因。我读到 C++ 中的 sizeof 空结构不为零，因为如果大小为 0 那么该类的两个对象将具有相同的地址，这是不可能的。我哪里错了？
Possible Duplicates:
Empty class in C++
What is the size of an empty struct in C?
I read somewhere that size of an empty struct in C++ is 1. So I thought of verifying it.
Unfortunately I saved it as a C file and used <stdio.h> header and I was surprised to see the output. It was 0.
That means
struct Empty {
};
int main(void)
{
printf("%d",(int)sizeof(Empty));
}
was printing 0 when compiled as a C file and 1 when compiled as a C++ file. I want to know the reason. I read that sizeof empty struct in C++ is not zero because if the size were 0 then two objects of the class would have the same address which is not possible. Where am I wrong?
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C 中不能有空结构。这是违反语法约束的。
然而，gcc 允许 C 中的空结构作为扩展。
此外，如果结构没有任何命名成员，则行为是未定义，因为
C99说：所以
，是的，空结构的大小是 C++ 不能为零 :)
You cannot have an empty structure in C. It is a syntactic constraint violation.
However gcc permits an empty structure in C as an extension.
Furthermore the behaviour is undefined if the structure does not have any named member because
C99says :So
And yes size of an empty struct is C++ cannot be zero :)
有几个很好的理由。其中，这是为了确保指向该结构的指针的指针算术不会导致无限循环。更多信息：
http://bytes.com /topic/c/insights/660463-sizeof-empty-class-struct-1-a
There are several good reasons. Among others, this is to ensure that pointer arithmetics over pointers to that structure don't lead to an infinite loop. More information:
http://bytes.com/topic/c/insights/660463-sizeof-empty-class-structure-1-a
这是一篇精彩的文章，描述了为什么会发生这种情况，更相关的是，解决它的（安全）方法:)
http: //www.cantrip.org/emptyopt.html
Here is a wonderful article describing why this occurs, and more pertinently, a (safe) way around it :)
http://www.cantrip.org/emptyopt.html