[英]C struct variable gets overwritten when assigining other variable a value
I'm writing a program that parses a string and stores its values in a struct.我正在编写一个程序来解析一个字符串并将其值存储在一个结构中。
My problem is, when I assign the value of u->id, u->login ... till u->created_at , works fine, but after I assign u->followers , u->id changes its value to " \\307UUUU" .我的问题是,当我分配u->id, u->login ... 的值时,直到u->created_at ,工作正常,但在我分配u->followers 后, u->id将其值更改为“\\ 307UUUU” 。 The same happens after when assigning set_user_public_gists(u, p);分配set_user_public_gists(u, p);后也会发生同样的情况; , login changes its value from login = 0x55555555c6c0 "lorraine94588" to login = 0x55555555c6c0 "\\240\\307UUUU" ; , login将其值从login = 0x55555555c6c0 "lorraine94588"更改为login = 0x55555555c6c0 "\\240\\307UUUU" ;
Why is it happening and how can i solve it?为什么会发生,我该如何解决?
user.c用户名
struct user {
char *id;
char *login;
char *type;
char *created_at;
char *followers;
char *follower_list;
char *following;
char *following_list;
char *public_gists;
char *public_repos;
};
USER create_user() {
USER u = malloc(sizeof(USER));
return u;
}
void delete_user(USER u) {
free(u);
}
void set_user_id(USER u, char *s) {
u->id = strdup(s);
}
void set_user_login(USER u, char *s) {
u->login = strdup(s);
}
void set_user_type(USER u, char *s) {
u->type = strdup(s);
}
void set_user_created_at(USER u, char *s) {
u->created_at = strdup(s);
}
void set_user_followers(USER u, char *s) {
u->followers = strdup(s);
}void set_user_follower_list(USER u, char *s) {
u->follower_list = strdup(s);
}
void set_user_following(USER u, char *s) {
u->following = strdup(s);
}
void set_user_following_list(USER u, char *s) {
u->following_list = strdup(s);
}
void set_user_public_gists(USER u, char *s) {
u->public_gists = strdup(s);
}
void set_user_public_repos(USER u,char *s) {
u->public_repos = strdup(s);
}
void set_user(USER u, char *line) {
char *p = NULL, *temp_line = line;
int i = 0;
while ((p = strsep(&temp_line, ";")) != NULL) {
switch (i) {
case 0:
set_user_id(u, p);
break;
case 1:
set_user_login(u, p);
break;
case 2:
set_user_type(u, p);
break;
case 3:
set_user_created_at(u, p);
break;
case 4:
set_user_followers(u, p);
break;
case 5:
set_user_follower_list(u, p);
break;
case 6:
set_user_following(u, p);
break;
case 7:
set_user_following_list(u, p);
break;
case 8:
set_user_public_gists(u, p);
break;
case 9:
set_user_public_repos(u, p);
break;
}
i++;
}
}
GDB广交会
79 set_user_followers(u, p);
(gdb) print u[0]
$14 = {id = 0x55555555c6a0 "6611157", login = 0x55555555c6c0 "lorraine94588", type = 0x55555555c6e0 "User",
created_at = 0x55555555c700 "2014-02-07 01:01:35",
followers = 0x37353131313636 <error: Cannot access memory at address 0x37353131313636>, follower_list = 0x0, following = 0x0,
following_list = 0x21 <error: Cannot access memory at address 0x21>,
public_gists = 0x656e696172726f6c <error: Cannot access memory at address 0x656e696172726f6c>,
public_repos = 0x3838353439 <error: Cannot access memory at address 0x3838353439>}
(gdb) n
80 break;
(gdb) print u[0]
$15 = {id = 0x55555555c6a0 " \307UUUU", login = 0x55555555c6c0 "lorraine94588", type = 0x55555555c6e0 "User",
created_at = 0x55555555c700 "2014-02-07 01:01:35", followers = 0x55555555c720 "0", follower_list = 0x0, following = 0x0,
following_list = 0x21 <error: Cannot access memory at address 0x21>,
public_gists = 0x656e696172726f6c <error: Cannot access memory at address 0x656e696172726f6c>,
public_repos = 0x3838353439 <error: Cannot access memory at address 0x3838353439>}
(gdb)
You allocate not enough bytes (I assume that USER is a pointer).您分配的字节不足(我假设 USER 是一个指针)。 Rather than reserving bytes for struct user
you allocate only enough bytes to handle a pointer to struct user
.您只分配足够的字节来处理指向struct user
的指针,而不是为struct user
保留字节。
Rather than:而不是:
USER u = malloc(sizeof(USER));
it should be它应该是
USER u = malloc(sizeof *u);
Two hints for future:对未来的两个提示:
sizeof
rather than type:在sizeof
使用实际对象而不是类型:x = malloc(sizeof *x);
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