指向stuct数据的指针 [英] pointer to stuct data

问题描述

你好，

我正在研究一个代码，它的数据结构如下：


typedef struct {

char * infile;

char inoptsbuf [10];

char * outfile;

} cmdoption_a;


cmdoption_a * cmdoption;


和初始化如下：


cmdoption-> infile = 1;

cmdoption-> outfile = 1;

cmdoption-> inoptsbuf =''\ 0'';


我真的很困惑，因为整数是分配给上面的变量吗？!!!!

任何帮助?? !!


bob

解决方案

Robert S写道：

hello，
我正在调查一个代码，其中包含如下数据结构：

typedef struct {
char * infile;
char inoptsbuf [10];
char * outfile;
} cmdoption_a;

cmdoption_a * cmdoption;

和初始化如下：

c mdoption-> infile = 1;
cmdoption-> outfile = 1;
cmdoption-> inoptsbuf =''\ 0'';

我真的很困惑因为整数是分配给上面的变量吗？!!!!
任何帮助?? !!

你*应该*混淆;代码（正如你所引用的那样）没有任何意义

，会（应该？）不能编译，当然也无法工作。


为什么不发布*真*代码（即剪切和粘贴，不要转录）？我是

肯定有人可以解决任何困惑。


HTH，

--ag


-

Artie Gold - 德克萨斯州奥斯汀
http://it-matters.blogspot.com （新帖子12/5）
http://www.cafepress.com/goldsays

thanks

它是一个转码器程序，编译运行没有问题

这里是代码：


typedef struct {


char * infile;

/ *输入图像文件。 * /


int infmt;

/ *输入图像文件格式。 * /


char * inopts;

char inoptsbuf [OPTSMAX + 1];


char * outfile;

/ *输出图像文件。 * /


int outfmt;


char * outopts;

char outoptsbuf [OPTSMAX + 1];


int verbose;

/ *详细模式。 * /


int debug;


int version;


int_fast32_t cmptno;


int srgb;


} cmdopts_t;

..

..

..

..

..

cmdopts_t * cmdopts;


cmdopts-> infile = 0;

cmdopts-> infmt = -1;

cmdopts-> inopts = 0;

cmdopts-> inoptsbuf [0] =''\''';

cmdopts-> outfile = 0;

cmdopts-> outfmt = -1;

cmdopts-> outopts = 0;

cmdopts-> outoptsbuf [0] =''\ 0'';

cmdopts - > verbose = 0;

cmdopts-> version = 0;

cmdopts-> cmptno = -1;

cmdopts- > debug = 0;

cmdopts-> srgb = 0;

..

..

..

..


" Artie Gold" < AR ******* @ austin.rr.com>在消息新闻中写道：3c ************* @ individual.net ...

Robert S写道：

你好，
typedef struct {
char * infile;
char inoptsbuf [10];
char * outfile;
} cmdoption_a;

cmdoption_a * cmdoption;

和初始化如下：

cmdoption-> infile = 1 ;
cmdoption-> outfile = 1;
cmdoption-> inoptsbuf =''\ 0'';

我真的很困惑，因为整数被分配给以上变量？!!!!
任何帮助?? !!

你*应该*混淆;代码（正如你所引用的那样）毫无意义
，（应该？）不能编译，当然也不可能工作。

为什么不发布*真正的*代码（即剪切和粘贴，不要转录）？我确定这里有人可以解决任何困惑。

HTH，
--ag

-
Artie Gold - 德克萨斯州奥斯汀
http://it-matters.blogspot.com （新帖子12/5）
http://www.cafepress.com / goldsays

请不要顶​​尖。你的回复属于下面的，或者用任何引用的文字穿插

。


在原始邮件中，你写道：

< blockquote class =post_quotes>

typedef struct {
char * infile;
char inoptsbuf [10];
char * outfile;
} cmdoption_a ;

cmdoption_a * cmdoption;

和初始化如下：

cmdoption-> infile = 1;
cmdoption-> outfile = 1;
cmdoption-> inoptsbuf =''\ 0'';

但实际代码说（修剪了一下）：

typedef struct {
char * infile;
[...] char * outfile;
[...] char outoptsbuf [OPTSMAX + 1];
[...]} cmdopts_t;
[...] cmdopts_t * cmdopts;

cmdopts-> infile = 0;
[...] cmdopts-> outfile = 0;
[...] cmdopts-> outoptsbuf [0] =''\''';

初始化一个带有1的指针几乎肯定会使没意义，但0

是一个空指针常量。我更喜欢使用宏NULL（在< stddef.h>和其他几个标准头文件中定义

），但是一个朴素的0

是完全合法的。


这就是为什么最好剪切并粘贴你要求的实际代码，而不是试图解释它;这很容易

意外地改变了你要问的事情。


-

Keith汤普森（The_Other_Keith） ks***@mib.org < http://www.ghoti.net/~kst>

圣地亚哥超级计算机中心< *> < http://users.sdsc.edu/~kst>

我们必须做点什么。这是事情。因此，我们必须这样做。

hello,
I am investigating a code,which has data struct deelacration as follow:

typedef struct {
char *infile;
char inoptsbuf[10];
char *outfile;
} cmdoption_a;

cmdoption_a *cmdoption;

and intialization as follow:

cmdoption->infile=1;
cmdoption->outfile=1;
cmdoption->inoptsbuf=''\0'';

I am really confused since an integer is assign to the above variables?!!!!
any help??!!

bob

解决方案

Robert S wrote:

hello,
I am investigating a code,which has data struct deelacration as follow:

typedef struct {
char *infile;
char inoptsbuf[10];
char *outfile;
} cmdoption_a;

cmdoption_a *cmdoption;

and intialization as follow:

cmdoption->infile=1;
cmdoption->outfile=1;
cmdoption->inoptsbuf=''\0'';

I am really confused since an integer is assign to the above variables?!!!!
any help??!!

You *should* be confused; the code (as you''ve quoted it) makes no sense
at all, would (should?) not compile and certainly couldn''t possibly work.

Why not post the *real* code (i.e. cut and paste, don''t transcribe)? I''m
sure someone here could clear up any confusion.

HTH,
--ag

--
Artie Gold -- Austin, Texas
http://it-matters.blogspot.com (new post 12/5)
http://www.cafepress.com/goldsays

thanks
It is a transcoder proram which compile and run without a problem
here is the code:

typedef struct {

char *infile;
/* The input image file. */

int infmt;
/* The input image file format. */

char *inopts;
char inoptsbuf[OPTSMAX + 1];

char *outfile;
/* The output image file. */

int outfmt;

char *outopts;
char outoptsbuf[OPTSMAX + 1];

int verbose;
/* Verbose mode. */

int debug;

int version;

int_fast32_t cmptno;

int srgb;

} cmdopts_t;
..
..
..
..
..
cmdopts_t *cmdopts;

cmdopts->infile = 0;
cmdopts->infmt = -1;
cmdopts->inopts = 0;
cmdopts->inoptsbuf[0] = ''\0'';
cmdopts->outfile = 0;
cmdopts->outfmt = -1;
cmdopts->outopts = 0;
cmdopts->outoptsbuf[0] = ''\0'';
cmdopts->verbose = 0;
cmdopts->version = 0;
cmdopts->cmptno = -1;
cmdopts->debug = 0;
cmdopts->srgb = 0;
..
..
..
..

"Artie Gold" <ar*******@austin.rr.com> wrote in message news:3c*************@individual.net...

Robert S wrote:

hello,
I am investigating a code,which has data struct deelacration as follow:

typedef struct {
char *infile;
char inoptsbuf[10];
char *outfile;
} cmdoption_a;

cmdoption_a *cmdoption;

and intialization as follow:

cmdoption->infile=1;
cmdoption->outfile=1;
cmdoption->inoptsbuf=''\0'';

I am really confused since an integer is assign to the above variables?!!!!
any help??!!

You *should* be confused; the code (as you''ve quoted it) makes no sense
at all, would (should?) not compile and certainly couldn''t possibly work.

Why not post the *real* code (i.e. cut and paste, don''t transcribe)? I''m
sure someone here could clear up any confusion.

HTH,
--ag

--
Artie Gold -- Austin, Texas
http://it-matters.blogspot.com (new post 12/5)
http://www.cafepress.com/goldsays

Please don''t top-post. Your response belongs below, or interspersed
with, any quoted text.

In your original message, you wrote:

typedef struct {
char *infile;
char inoptsbuf[10];
char *outfile;
} cmdoption_a;

cmdoption_a *cmdoption;

and intialization as follow:

cmdoption->infile=1;
cmdoption->outfile=1;
cmdoption->inoptsbuf=''\0'';

but the actual code says (trimmed a bit):
typedef struct {
char *infile; [...] char *outfile; [...] char outoptsbuf[OPTSMAX + 1]; [...] } cmdopts_t; [...] cmdopts_t *cmdopts;

cmdopts->infile = 0; [...] cmdopts->outfile = 0; [...] cmdopts->outoptsbuf[0] = ''\0'';

Initializing a pointer with 1 almost certainly makes no sense, but 0
is a null pointer constant. I''d prefer to use the macro NULL (defined
in <stddef.h> and several other standard headers), but an unadorned 0
is perfectly legal.

This is why it''s best to cut-and-paste the actual code you''re asking
about rather than trying to paraphrase it; it''s too easy to
accidentally change the very thing you''re asking about.

--
Keith Thompson (The_Other_Keith) ks***@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <*> <http://users.sdsc.edu/~kst>
We must do something. This is something. Therefore, we must do this.

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