從文件讀取鏈接列表並加載數據

Question

我編寫了一個C代碼來實現使用鏈接列表的字典（節點按排序順序）我想將數據保存到文件並能夠在數據重新加載時我下次運行這個程序。我無法從文件加載數據。這裏是我的讀取和寫入數據的代碼：

struct node{ 
    char word[20]; 
    char meaning[5][100]; //2D array for saving multiple meanings of a word 
    struct node *next; 
}; 

void ReadData(struct node *head) 
{ 
    struct node *tail; 
    FILE *fp = fopen("dictionary.data", "rb"); 
    if(fp == NULL) 
    { 
     printf("Error opening file..\n"); 
     return; 
    } 
    while(!feof(fp)) 
    { 
     tail = (struct node*)calloc(1, sizeof(struct node)); 
     fread(tail->word, sizeof(head->word), 1, fp); 
     fread(tail->meaning, sizeof(head->meaning), 1, fp); 
     if(head == NULL) //for fresh run head is initialized with NULL 
     { 
      tail->next = head; 
      head = tail; 
     } 
     else 
     { 
      head->next = tail; 
      head = head->next; 
     } 
    } 
    fclose(fp); 
} 

我無法從文件到鏈接列表加載數據。代碼不起作用。我想不通問題出在哪裏..
這裏是我如何將數據寫入文件：

/*I think this code is working because size of the file increases after running the code*/ 
void WriteData(struct node *head) 
{ 
    FILE *fp = fopen("dictionary.data", "wb"); 
    if(fp == NULL) 
    { 
     printf("Error opening file..\n"); 
     return; 
    } 
    while(head != NULL) 
    { 
     fwrite(head->word, sizeof(head->word), 1, fp); 
     fwrite(head->meaning, sizeof(head->meaning), 1, fp); 
     head = head->next; 
    } 
    fclose(fp); 
} 

我用sizeof，而不是strlen，這是一個字符串。它最後會有空字符 - 沒有問題的字符串。它會消耗更多的內存。

Answer 1

嘗試這種（未經測試）：

void ReadData(struct node **head){//or struct node *ReadData(void){ ... return head; } 
    struct node temp = { .next = NULL };//{ {0}, {{0}}, NULL} 
    struct node *hp, *curr; 
    FILE *fp = fopen("dictionary.data", "rb"); 

    if(fp == NULL){ 
     printf("Error opening file..\n"); 
     return; 
    } 

    hp = *head; 
    while(fread(temp.word, sizeof(temp.word), 1, fp) && fread(temp.meaning, sizeof(temp.meaning), 1, fp)){ 
     struct node *np = malloc(sizeof(*np)); 
     if(np == NULL){ 
      perror("couldn't make new node by malloc:"); 
      return ;//release list 
     } 
     *np = temp; 

     if(hp == NULL){//for fresh run head is initialized with NULL 
      curr = hp = np; 
     } else {//If *head isn't NULL, you need to move to the last node first. 
      curr = curr->next = np; 
     } 
    } 
    fclose(fp); 
    *head = hp; 
} 
//.................... 
int main(void){ 
    //... 
    struct node *head = NULL; 
    //... 
    ReadData(&head); 
    //...