[英]C struct variable gets overwritten when assigining other variable a value
我正在編寫一個程序來解析一個字符串並將其值存儲在一個結構中。
我的問題是,當我分配u->id, u->login ... 的值時,直到u->created_at ,工作正常,但在我分配u->followers 后, u->id將其值更改為“\\ 307UUUU” 。 分配set_user_public_gists(u, p);后也會發生同樣的情況; , login將其值從login = 0x55555555c6c0 "lorraine94588"更改為login = 0x55555555c6c0 "\\240\\307UUUU" ;
為什么會發生,我該如何解決?
用戶名
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++;
}
}
廣交會
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)
您分配的字節不足(我假設 USER 是一個指針)。 您只分配足夠的字節來處理指向struct user
的指針,而不是為struct user
保留字節。
而不是:
USER u = malloc(sizeof(USER));
它應該是
USER u = malloc(sizeof *u);
對未來的兩個提示:
sizeof
使用實際對象而不是類型:x = malloc(sizeof *x);
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