一个元素数组作为struct typedef的名称 [英] one element array as name of struct typedef
问题描述
我在讨论GNU
MP库如何实现其mpz_t类型时碰到了以下内容。
typedef struct {
int len;
char * buf;
} foo [1];
这是一项有趣的技巧。我不熟悉将typedef的
名称声明为单元素数组。这是C
标准的一部分吗？它是便携式的吗？这种技术有名吗？
I ran into something like the following while looking into how the GNU
MP library implements its mpz_t type.
typedef struct {
int len;
char *buf;
} foo[1];
This is an interesting technique. I''m unfamiliar with declaring the
name of a typedef as a one element array. Is this part of the C
standard? Is it portable? Does this technique have a name?
推荐答案
Ron Peterson（012ED25E）写道：
Ron Peterson (012ED25E) wrote:
我在调查GNU
MP库如何实现其mpz_t类型时碰到了以下内容。
typedef struct {
int len;
char * buf;
} foo [1];
这是一个有趣的技术。我不熟悉将typedef的
名称声明为单元素数组。这是C
标准的一部分吗？它是便携式的吗？这种技术有名字吗？
I ran into something like the following while looking into how the GNU
MP library implements its mpz_t type.
typedef struct {
int len;
char *buf;
} foo[1];
This is an interesting technique. I''m unfamiliar with declaring the
name of a typedef as a one element array. Is this part of the C
standard? Is it portable? Does this technique have a name?
嗯....我想你错了这意味着什么。
我的阅读（可能容易不正确的是它使得foo a
typedef，用于单个维度，单个元素，此类结构的数组。
我正试图找出这种技术的价值会是。
Hmmm.... I think you''re mistaken in what this means.
My reading (which could easily be incorrect) is that it makes "foo" a
typedef for a single dimension, single element, array of such structures.
I''m trying to work out what the value of such a technique would be.
在文章< fb ********** @ aioe.org>，
Mark Bluemel< ; ma ********** @ pobox.comwrote：
In article <fb**********@aioe.org>,
Mark Bluemel <ma**********@pobox.comwrote:
> typedef struct {
int len;
char * buf;
} foo [1];
>typedef struct {
int len;
char *buf;
} foo[1];
>我正在试图找出这种技术的价值。
>I''m trying to work out what the value of such a technique would be.
我的猜测是，通过引用自动传递（
效果）对象是一个巧妙的技巧。如果它是
typedef struct {...} foo;
你将不得不在整个地方使用& foo，并且它已经是
typedef struct {...} * foo;
你必须分配数据以及声明一个变量。
- Richard
-
应考虑多达32个的需要字符
某些字母表中的
" - X3.4,1963。
My guess is that it''s a neat trick for having objects that are (in
effect) automatically passed by reference. If it had been
typedef struct {...} foo;
you would have to use &foo all over the place, and it it had been
typedef struct {...} *foo;
you would have to allocate the data as well as declaring a variable.
-- Richard
--
"Consideration shall be given to the need for as many as 32 characters
in some alphabets" - X3.4, 1963.
我在研究GNU如何时遇到了类似的问题>
MP库实现其mpz_t类型。
typedef struct {
int len;
char * buf;
} foo [1];
这是一项有趣的技巧。我不熟悉将typedef的
名称声明为单元素数组。这是C
标准的一部分吗？它是便携式的吗？这种技术有名字吗？
I ran into something like the following while looking into how the GNU
MP library implements its mpz_t type.
typedef struct {
int len;
char *buf;
} foo[1];
This is an interesting technique. I''m unfamiliar with declaring the
name of a typedef as a one element array. Is this part of the C
standard? Is it portable? Does this technique have a name?
typeof（foo）== 1元素给定结构的数组
因此可以声明实际数组或定义为：
foo fooarray; / *注意：不需要尺寸信息* /
这个技术在指向数组的指针时很有用（我指的是整个数组，而不是
只是指向元数据类型）是必需的。
阅读C FAQ。 Ther是关于指针和数组的整整一章。
typeof(foo) == array of the given struct of 1 element
so the actual array may be declared or defined as:
foo fooarray; /* Note: No dimension info required */
the technique is useful when a pointer to an array (i mean entire array, not
just pointer to element data type) is required.
read C FAQ. Ther is a entire chapter devoted to pointers and array.
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