为什么我不能用具有相同内容的两个结构交替分配？ [英] Why can I not assign interchangeably with two structs that have identical contents?

问题描述

我想学习C和我遇到一些奇怪的：

I'm trying to learn C and I've come across something weird:

struct
{
  int i;
  double j;
} x, y;

struct
{
  int i;
  double j;
} z;

在这里，你可以看到我创建了两个结构 S中的是在他们的元素是相同的。

Here, you can see I created two structs that are identical in their elements.

为什么当我尝试分配 X = Z 它会产生一个编译错误，但 X = Y 不？他们有相同的内容，所以为什么我不能为它们分配来回相互搭配，不管？

Why is it that when I try to assign x = z it will generate a compile error but x = y does not? They have the same contents, so why can't I assign them back and forth with each other, regardless?

有没有什么办法可以让这个所以我的可以指定 X = Z ？或者，他们根本是相同的结构。

Is there any way I can make this so I can assign x = z? Or do they simply have to be the same struct.

所有C大师可以点我在正确的方向？

Can any C gurus point me in the right direction?

推荐答案

它们具有相同的内容，但不是同一类型。如果它们旨在是同一类型的，只要的typedef X Z; 。如果它们不一样的东西，但只是碰巧包含相同的领域，最好是创建一个单独的功能，将正确地分配等领域。

They have the same content, but not the same type. If they are intended to be of the same type, simply typedef x z;. If they aren't the same thing, but just happen to contain the same fields, it's better to create a separate function that will assign the fields properly.

---

我一贯的风格在C声明结构包含了类型定义，所以我忘了提到它（对不起！）。下面是语法：

My usual style for declaring structs in C includes the typedef, so I forgot to mention it (sorry!). Here's the syntax:

typedef struct
{
  int foo;
  double bar;
} x;

/* Further down, if needed */
typedef x z;

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