Private structures for that file should go in the .c file, with a declaration in the .h file if they are used by any functions in the .h .

Public structures should go in the .h file.

两者都应带来同样的可使用性,即使通过联系,也应当加以控制?

No, not when you consider other .c files including the same header. If the definition of the structure is not visible to the compiler, the details of that definition cannot be used. A declaration without a definition (e.g. just struct s;) causes the compiler to fail if anything tries to look inside struct s, while still allowing it to e.g. compile struct s *foo; (as long as foo is not later dereferenced).

比较<代码>api.h和api.c:

Definition in header:                 Definition in implementation:
+---------------------------------+   +---------------------------------+
| struct s {                      |   | struct s;                       |
|     int internal;               |   |                                 |
|     int other_stuff;            |   | extern void                     |
| };                              |   | api_func(struct s *foo, int x); |
|                                 |   +---------------------------------+
| extern void                     |   +---------------------------------+
| api_func(struct s *foo, int x); |   | #include "api.h"                |
+---------------------------------+   |                                 |
+---------------------------------+   | struct s {                      |
| #include "api.h"                |   |     int internal;               |
|                                 |   |     int other_stuff;            |
| void                            |   | };                              |
| api_func(struct s *foo, int x)  |   |                                 |
| {                               |   | void                            |
|     foo->internal = x;          |   | api_func(struct s *foo, int x)  |
| }                               |   | {                               |
+---------------------------------+   |     foo->internal = x;          |
                                      | }                               |
                                      +---------------------------------+

该信标的客户有两种版本:

#include "api.h"

void good(struct s *foo)
{
    api_func(foo, 123);
}

在执行过程中,有一个oke子:

#include "api.h"

void bad(struct s *foo)
{
    foo->internal = 123;
}

它将采用“头盔定义”版本,但不采用“执行中的定义”版本,因为在后一种情况下,汇编者对结构的布局不了解:

$ gcc -Wall -c bad.c
bad.c: In function  bad :
bad.c:5: error: dereferencing pointer to incomplete type
$

因此,“执行中的定义”版本保护不受意外或蓄意滥用私人执行细节的影响。

如果要由其他汇编单位(c文档)使用,则将其放在标题档案中,这样,只要需要,你就能够包括该标题档案。

如果单元仅用于一个汇编单位(文档),则将其放在该档案中。

The point is, placing it in a header file allows you to use the structure (or any other definition) from multiple source files, just by including that header file.

但是,如果你确信,它只能从一个来源档案中使用,那么它实际上不会有任何改变。

我将这些文件放在C档案中,使其更加客观,。