零元素数组 [英] Array of zero element
问题描述
我看到一些代码是我们有零元素的数组（大多数是结构内的
）
喜欢，
typedef struct foo {
int data [0]
} foo;
只是好奇使用这种代码是什么？以及如何使用struct foo的成员
变量'data''？
谢谢，
Nilesh
Hi,
I have seen some code were we have array with zero elements (mostly
within structure)
like,
typedef struct foo {
int data[0]
}foo;
Just curious whats the use of this kind of code ? And how to use member
variable ''data'' of struct foo ?
Thanks,
Nilesh
推荐答案
ni *** ********@gmail.com 说：
我有看到一些代码是我们有零元素的数组（大多数是结构内的
）
喜欢，
typedef struct foo {
int data [0]
} foo;
只是好奇使用这种代码是什么？
Hi,
I have seen some code were we have array with zero elements (mostly
within structure)
like,
typedef struct foo {
int data[0]
}foo;
Just curious whats the use of this kind of code ?
它有助于生成诊断消息，例如：
警告：ANSI C禁止零大小的数组`data''
警告：结构或联合结尾没有分号
It''s good for generating diagnostic messages, such as:
warning: ANSI C forbids zero-size array `data''
warning: no semicolon at end of struct or union
如何使用会员
struct foo的变量''data''？
And how to use member
variable ''data'' of struct foo ?
使它大于0，最后粘贴分号，实例化，
然后使用成员运算符。访问会员对象。
-
Richard Heathfield
Usenet是一个奇怪的地方 - dmr 29/7/1999
http://www.cpax.org.uk
电子邮件：rjh在上述域名， - www。
Make it a big bigger than 0, stick a semicolon on the end, instantiate it,
and then use the member operator . to access the member object.
--
Richard Heathfield
"Usenet is a strange place" - dmr 29/7/1999
http://www.cpax.org.uk
email: rjh at the above domain, - www.
Richard Heathfield写道：
Richard Heathfield wrote:
ni *********** @ gmail.com 说：
我见过一些代码，我们有数组为零元素（大多数是结构内的
）
喜欢，
typedef struct foo {
int data [0]
} foo;
只是好奇使用这种代码是什么？
Hi,
I have seen some code were we have array with zero elements (mostly
within structure)
like,
typedef struct foo {
int data[0]
}foo;
Just curious whats the use of this kind of code ?
它有助于生成诊断消息，例如：
警告：ANSI C禁止零大小数组`data''
警告：结构或联合结束时没有分号
It''s good for generating diagnostic messages, such as:
warning: ANSI C forbids zero-size array `data''
warning: no semicolon at end of struct or union
好的，我用分号和编译使用gcc，它不是产生警告，
Ok, I put semicolon and compiling using gcc, its not producing warning,
>
>
如何使用成员
struct foo的变量''data''？
And how to use member
variable ''data'' of struct foo ?
使它大于0，最后粘贴分号，实例化，
然后使用成员运算符。访问会员对象。
-
Richard Heathfield
Usenet是一个奇怪的地方 - dmr 29/7/1999
http://www.cpax.org.uk
电子邮件：rjh在上述域名， - www。
Make it a big bigger than 0, stick a semicolon on the end, instantiate it,
and then use the member operator . to access the member object.
--
Richard Heathfield
"Usenet is a strange place" - dmr 29/7/1999
http://www.cpax.org.uk
email: rjh at the above domain, - www.
ni * **********@gmail.com 写道：
我看到一些代码是我们有零元素的数组（大多数结构中是
）
喜欢，
typedef struct foo {
int data [0]
} foo;
只是好奇什么是使用这种代码？以及如何使用成员
struct foo的变量''data''
谢谢，
Nilesh
Hi,
I have seen some code were we have array with zero elements (mostly
within structure)
like,
typedef struct foo {
int data[0]
}foo;
Just curious whats the use of this kind of code ? And how to use member
variable ''data'' of struct foo ?
Thanks,
Nilesh
零长度数组不是标准C，而是GCC扩展。在
书中GCC - 完整参考，据说：
" GNU C允许声明零长度数组以方便
创建
可变长度结构。这只有在零长度
数组是结构的最后一个
成员时才有意义。数组的大小可以简单地指定
分配
所需的空间量。以下程序演示了
技术：
/ * zarray.c * /
#include< stdio.h>
typedef struct {
int size;
char string [0];
} vlen;
int main（int argc，char * argv []）
{
int i;
int count = 22;
char letter =''a'';
vlen * line =（vlen *）malloc（sizeof（vlen）+ count）;
line-> ; size = count;
for（i = 0; i< count; i ++）
line-> string [i] = letter ++;
printf（" sizeof（vlen）=％d \ n"，sizeof（vlen））;
for（i = 0; i< line-> size; i ++）
printf（"％c"，line-> string [i]）;
printf（" \ n"）;
返回（0）;
}
"
Array of zero length is NOT standard C, but a GCC extension. In the
book "GCC - The Complete Reference", it is said that:
"GNU C allows the declaration of arrays of zero length to facilitate
the creation of
variable-length structures. This only makes sense if the zero-length
array is the last
member of a struct. The size of the array can be specified by simply
being allocated
the amount of space necessary. The following program demonstrates the
technique:
/* zarray.c */
#include <stdio.h>
typedef struct {
int size;
char string[0];
} vlen;
int main(int argc,char *argv[])
{
int i;
int count = 22;
char letter = ''a'';
vlen *line = (vlen *)malloc(sizeof(vlen) + count);
line->size = count;
for(i=0; i<count; i++)
line->string[i] = letter++;
printf("sizeof(vlen)=%d\n",sizeof(vlen));
for(i=0; i<line->size; i++)
printf("%c ",line->string[i]);
printf("\n");
return(0);
}
"
这篇关于零元素数组的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
