vc.user_comments [i] = string; / * *崩溃/ [英] vc.user_comments[i] = string; /*crashing*/
问题描述
有这种结构：
typedef struct {
char ** user_comments;
/ * ... * /
} vorbis_comment;
/ * prototype * /
char * read_vorbis_string
（文件* sc）;
/ *问题* /
vc.user_comments [i] = read_vorbis_string（sc）;
''read_vorbis_string''返回一个指向calloced字符串的指针。这个函数
肯定是有用的。
但问题是，'vc.user_comments [i] = string;''不是正确的方式
将''字符串''的地址分配给指针数组''vc.user_comments''。
什么是？
Have this kind of struct:
typedef struct {
char **user_comments;
/* ... */
} vorbis_comment;
/* prototype */
char * read_vorbis_string
( FILE *sc);
/* problem */
vc.user_comments[i] = read_vorbis_string (sc);
''read_vorbis_string'' returns a pointer to a calloced string. This function
works for sure.
But the problem is, that ''vc.user_comments[i] = string;'' is not the right way
to assing the address of the ''string'' to the pointer array ''vc.user_comments''.
What is?
推荐答案
" Tatu Portin" <斧**** @ mbnet.fi>在消息中写道
news：xV ************** @ read3.inet.fi ...
"Tatu Portin" <ax****@mbnet.fi> wrote in message
news:xV**************@read3.inet.fi...
有这种结构：
typedef struct {
char ** user_comments;
/ * ... * /
} vorbis_comment;
/ * prototype * /
char * read_vorbis_string
（文件* sc）;
/ *问题* /
vc.user_comments [i] = read_vorbis_string（sc）;
''read_vorbis_string''返回一个指向calloced字符串的指针。这个功能确实有用。
但问题是，''vc.user_comments [i] = string;''不是正确的
方式来确定''的地址字符串''到指针数组
''vc.user_comments''。是什么？
Have this kind of struct:
typedef struct {
char **user_comments;
/* ... */
} vorbis_comment;
/* prototype */
char * read_vorbis_string
( FILE *sc);
/* problem */
vc.user_comments[i] = read_vorbis_string (sc);
''read_vorbis_string'' returns a pointer to a calloced string. This function
works for sure.
But the problem is, that ''vc.user_comments[i] = string;'' is not the right way to assing the address of the ''string'' to the pointer array ''vc.user_comments''. What is?
你已经忘记了vorbis_comment的实施。请发布这个
部分，声明并初始化vc。
karl m
You''ve left out the INSTANTIATION of vorbis_comment. Please post this
section, where you declare and initialize vc.
karl m
karl malbrain写道：
karl malbrain wrote:
" Tatu Portin" <斧**** @ mbnet.fi>在消息中写道
新闻：xV ************** @ read3.inet.fi ...
"Tatu Portin" <ax****@mbnet.fi> wrote in message
news:xV**************@read3.inet.fi...
有这种结构：
typedef struct {
char ** user_comments;
/ * ... * /
} vorbis_comment;
/ * prototype * /
char * read_vorbis_string
（文件* sc）;
/ *问题* /
vc.user_comments [i] = read_vorbis_string（sc）;
''read_vorbis_string''返回一个指向calloced字符串的指针。这个功能确实有用。
但问题是，''vc.user_comments [i] = string;''不是正确的
Have this kind of struct:
typedef struct {
char **user_comments;
/* ... */
} vorbis_comment;
/* prototype */
char * read_vorbis_string
( FILE *sc);
/* problem */
vc.user_comments[i] = read_vorbis_string (sc);
''read_vorbis_string'' returns a pointer to a calloced string. This function
works for sure.
But the problem is, that ''vc.user_comments[i] = string;'' is not the right
方式
way
将''字符串''的地址分配给指针数组
to assing the address of the ''string'' to the pointer array
''vc.user_comments''。
''vc.user_comments''.
什么是？
你已经忘记了vorbis_comment的实施。请发布此
部分，声明并初始化vc。
karl m
You''ve left out the INSTANTIATION of vorbis_comment. Please post this
section, where you declare and initialize vc.
karl m
这是你的 ; INSTANTIATION"：
vorbis_comment read_comments
（const char * scname）
{
/ *在第二个''vorbis'之后，字符串出现了VENDOR字符串的宽度（int）。
*然后是VENDOR字符串本身。
*在VENDOR字符串出现之后（int）评论。
*评论数量来自第一个用户评论的宽度（int）。
*第一个用户评论后出现宽度（int ）第二个用户评论。
* /
注册int i;
vorbis_comment vc;
FILE * sc;
char * ident =" vorbis";
sc = fopen（scname，" rb"）;
断言（sc！= NULL）;
断言（！wind_till（ident，sc））;
断言（！wind_till（ident） ，sc））;
vc.vend或= read_vorbis_string（sc）;
断言（vc.vendor！= NULL）;
断言（fread（& vc.comments，sizeof（int） ），1，sc）== 1）;
printf（"％d \ nn"，vc.comments）;
vc.comment_wds =（int *）calloc（vc.comments + 1，sizeof（int））;
断言（vc.comment_wds！= NULL）;
$ （b = b;（i = 0;我< vc.comments - 1; i ++）{
vc.user_comments [i] = read_vorbis_string（sc）;
assert（vc.user_comments [i]！= NULL）;
printf（" __％s __"，vc.user_comments [i]）;
vc.comment_wds [i] = strlen（vc.user_comments [i] ）;
}
vc.comment_wds [vc.comments + 1] = 0;
return vc;
}
/ *文件结尾* /
Here is your "INSTANTIATION":
vorbis_comment read_comments
( const char *scname)
{
/* After second ''vorbis'' string comes the width (int) of VENDOR string.
* Then comes the VENDOR string itself.
* After VENDOR string comes the number (int) of comments.
* After the number of comments comes the width (int) of first user comment.
* After the first user comment comes the width (int) of the second user comment.
*/
register int i;
vorbis_comment vc;
FILE *sc;
char *ident = "vorbis";
sc = fopen (scname, "rb");
assert (sc != NULL);
assert (!wind_till (ident, sc));
assert (!wind_till (ident, sc));
vc.vendor = read_vorbis_string (sc);
assert (vc.vendor != NULL);
assert (fread (&vc.comments, sizeof (int), 1, sc) == 1);
printf ("%d\n", vc.comments);
vc.comment_wds = (int *) calloc (vc.comments + 1, sizeof (int));
assert (vc.comment_wds != NULL);
for (i = 0 ; i < vc.comments - 1 ; i++) {
vc.user_comments[i] = read_vorbis_string (sc);
assert (vc.user_comments[i] != NULL);
printf ("__%s__", vc.user_comments[i]);
vc.comment_wds[i] = strlen (vc.user_comments[i]);
}
vc.comment_wds[vc.comments + 1] = 0;
return vc;
}
/* End Of File */
问题解决了。
我没有为指针数组调用内存。我只是为指针数组指向的字符串调用内存
。
/ * ... * /
断言（fread（& vc.comments，sizeof（int），1，sc）== 1）;
printf（"％d \\ \\ n"，vc.comments）;
/ * ADDED * /
vc.user_comments =（char *）calloc（vc.comments + 1， sizeof（char *））;
断言（vc.user_comments！= NULL）;
/ *加入结束* /
vc.comment_wds =（int *）calloc（vc.comments + 1，sizeof（int））;
断言（vc.comment_wds！= NULL）;
/ * ... * /
Problem solved.
I hadn''t calloced memory for the array of pointers. I was only callocing memory
for the strings which the array of pointers should be pointing to.
/* ... */
assert (fread (&vc.comments, sizeof (int), 1, sc) == 1);
printf ("%d\n", vc.comments);
/* ADDED */
vc.user_comments = (char *) calloc (vc.comments + 1, sizeof (char *));
assert (vc.user_comments != NULL);
/* End of ADDED */
vc.comment_wds = (int *) calloc (vc.comments + 1, sizeof (int));
assert (vc.comment_wds != NULL);
/* ... */
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