我正在尝试在 C 中实现链表。我使用了一个名为 NODE 的结构。出于某种原因，我Segmentation Error 11在调用函数时得到了 a createList()。我调试了我的代码，我非常有信心这里会发生错误：
/* Write into node */
strcpy(head->username, cur_username);
strcpy(head->password, cur_pw);
strcpy(head->type, cur_type);
printf("%s %s %s\n", head->username, head->password, head->type);
我认为错误是因为内存分配不正确。但是我为每个节点值初始化了一个包含 50 个字符的数组，那么程序不应该自己管理内存吗？
char *filename = "password.csv";
int n_users = 0;
struct NODE {
char username[50];
char password[50];
char type[50];
struct NODE *next;
} *head=NULL, *curr=NULL;
/* Global placeholders so they can be used by other both add() and creatList() */
char line[50], *cur_username, *cur_pw, *cur_type;
char linecopy[50];
void createList(void) {
printf("Creating list\n");
bool success;
/* Open the file in read-only and copy content into array */
/* File pointer */
FILE *f;
/* Node pointer */
struct NODE * ptr = (struct NODE*) malloc(sizeof(struct NODE));
if (NULL == ptr) {
printf("\nError: was unable to initialize password validation information!! \n");
return;
}
head = curr = ptr;
/* Open the file in read */
f = fopen("password.csv", "r");
/* if f == NULL, there was an error - the file probably does not exist. We don't care, we will create the file later */
if (f != NULL) {
/* Read the file line by line */
while(fgets(line, 49, f) != NULL) {
struct NODE * p = (struct NODE*) malloc(sizeof(struct NODE));
/* Copy line into linecopy because strtok is destructive */
strcpy(linecopy, line);
/* Extract the ids from linecopy */
cur_username = strtok(linecopy, ",");;
cur_pw = strtok(NULL, ",");
cur_type = strtok(NULL, ",");
if(head==NULL)
add(head);
else
add(p);
if (!success) {
printf("\nError: was unable to initialize password validation information!! \n");
return;
}
}
}
/* Close file */
fclose(f);
}
** HEAD 为 NULL **
虽然我不再有任何分段错误，但我的头没有被初始化......我正在从文件中读取输入并为文件的每一行创建一个节点。因此，我正在测试 head==NULL 并将 head 发送到 add(struct *NODE)。那不应该初始化头部吗？
struct NODE {
char username[50];
char password[50];
char type[50];
struct NODE *next;
} *head=NULL, *curr=NULL;
/* Global placeholders so they can be used by other both add() and creatList() */
char line[50], *cur_username, *cur_pw, *cur_type;
char linecopy[50];
void createList(void) {
printf("Creating list\n");
bool success;
/* Open the file in read-only and copy content into array */
/* File pointer */
FILE *f;
/* Node pointer */
struct NODE * ptr = (struct NODE*) malloc(sizeof(struct NODE));
if (NULL == ptr) {
printf("\nError: was unable to initialize password validation information!! \n");
return;
}
head = curr = ptr;
/* Open the file in read */
f = fopen("password.csv", "r");
/* if f == NULL, there was an error - the file probably does not exist. We don't care, we will create the file later */
if (f != NULL) {
/* Read the file line by line */
while(fgets(line, 49, f) != NULL) {
struct NODE * p = (struct NODE*) malloc(sizeof(struct NODE));
/* Copy line into linecopy because strtok is destructive */
strcpy(linecopy, line);
/* Extract the ids from linecopy */
cur_username = strtok(linecopy, ",");;
cur_pw = strtok(NULL, ",");
cur_type = strtok(NULL, ",");
if (head == NULL)
success = add(head);
else
success = add(p);
if (!success) {
printf("\nError: was unable to initialize password validation information!! \n");
return;
}
}
}
/* Close file */
fclose(f);
}