消失的字符串

Question

這是我第一篇文章，所以我提前感謝所有人提供任何幫助。

我遇到了消失的信息問題。該程序應該從文件中讀取書目標題和庫ID號，創建一個鏈接列表的哈希表，其中每個節點包含一個書結構，該書結構包含書的標題，另一個鏈接列表包含書ID所在的庫ID被發現。在這一點上，我只是試圖填充哈希表，但由於某種原因，我的標題值正在消失。文件格式如下：

2345，老人和海
567434，哈利·波特
1233，學習
等藝術...

我

typedef NodeStruct {void* data; NodePtr prev; NodePtr next;} NodeStruct; 

typedef NodeStruct* NodePtr; 

typedef ListStruct {NodePtr first; NodePtr last; NodePtr current; } ListStruct; 

typedef ListStruct* ListHndl; 

typedef BookStruct {char* title; ListHndl lib; } BookStruct; 

typedef BookStruct* BookHndl; 

FILE *fileptr; 
int numlines; 
int numslots; 
int i; 
int index; 
NodePtr fillnode; 


int main(int argc, char *argv[]) { 
    fileptr = fopen(argv[1], "r"); 

    if (!fileptr) { 
     printf("Error: cannot open file\n"); 
     return 1; 
    } 
    int *libID = malloc(sizeof(int)); 
    printf("(main) libID: %p\n", libID); 
    fscanf(fileptr, "%d %d", &numlines, &numslots); 
    printf("(main) numlines: %d numslots: %d\n", numlines, numslots); 
    ListHndl *H = calloc(numslots, sizeof(ListHndl)); 
    printf("(main) calloc iterated\n"); 

    for (i = 0; i < numlines; i++) { 
     printf("*************LOOP #%d*************\n", i); 
     char *title = malloc(sizeof(char) * 50); 
     if (fscanf(fileptr, "%d%*c%*c%[^\n]", libID, title) == 0) { 
      printf("Error: incorrect # of keys\n"); 
      return 1; 
     } 
     printf("(main) book: %s ID: %d\n", title, *libID); 
     index = hash(title, numslots); 
     printf("(main) index: %d\n", index); 
     printf("(main) hash[index]: %p\n", H[index]); 
     if (H[index] == NULL) { 
      H[index] = newList(); 
      printf("(main_if_H_NULL) hash[index]: %p\n", H[index]); 
      BookHndl B = newBook(title, libID); 
      printf("(main_if_H_NULL) BookHndl B: %p\n", B); 
      insertAtFront(H[index],(void *) B); 
      printf("(main_if_H_NULL) H[index] title: %s ID: %d\n", ((BookHndl) H[index]->first->data)->title, 
         *((int *) ((BookHndl) H[index]->first->data)->lib->first->data)); 
     } 
     printAll(H, numslots); 
     NodePtr S = searchTitle(H[index], title); 
     printf("(main) NodePtr S: %p\n", S); 
     if (S == NULL) { 
      BookHndl B = newBook(title, libID); 
      insertAtBack(H[index], (void *) B); 
      printf("(main_if_!S) inserted book\n"); 
     } else { 
      printf("(main_if_S)\n"); 
      ListHndl idL = ((BookHndl) S->data)->lib; 
      if (searchID(idL, libID) == 0) { 
       insertAtBack(idL, (void *) libID); 
       printf("(main_if_S) inserted libID\n"); 
      } 
     } 
     free((char *) title); 
     free((NodePtr) S); 
     printAll(H, numslots); 
     printf("hash[%d]: %s in library # %d\n", index, title, *libID); 
    } 

    return 1; 
} 

實際上有四個fscanf參數％d用於libID，％* c跳過「，」，另一個％* c跳過「」，％[^/n]讀取標題直到讀取換行符。在確認libID和標題中的正確值之後不久，print語句。在printAll（H，numslots）中，所有值都存在，返回NodePtr S = searchTitle（H [index]，title）後，標題消失。以下是我的新書和searchTitle功能

BookHndl newBook(char* str, int* ID) { 
    BookHndl B = malloc(sizeof(BookStruct)); 
    /*B->title = malloc(sizeof(char) * 50);*/ 
    B->title = strdup(str); 
    printf("(newBook) B->title = %s\n", B->title); 
    B->lib = newList(); 
    printf("(newBook) B->lib = %p\n", B->lib); 
    insertAtFront(B->lib, (void *) ID); 
    printf("(newBook) B->lib->first = %d\n", *((int *)B->lib->first->data)); 

    return B; 
} 

NodePtr searchTitle(ListHndl L, char* key) { 
    assert(L != NULL); 
    if (isEmpty(L)) { 
     printf("Book list empty\n"); 
     return NULL; 
    } else { 
     L->current = L->first; 
     printf("(searchTitle) ListHndl L = %p, L->first = %p, L->first->data = %p\n", L, L->first, (BookHndl) L->first->data); 
     while (L->current != NULL) { 
      BookHndl B = malloc(sizeof(BookStruct)); 
      B = (BookHndl) L->current->data; 
      printf("(searchTitle) bookhandle B = %p\n", B); 
      printf("(searchTitle) B->title = %s\n B->ID = %d\n", B->title, *((int *) B->lib->first->data)); 
      if (strcmp(B->title, key) == 0) { 
       free(B); 
       return L->current; 
      } 
      free(B); 
      L->current = L->current->next; 
     } 
    } 
    return NULL; 
} 

Answer 1

此代碼已損壞。

BookHndl B = malloc(sizeof(BookStruct)); 
B = (BookHndl) L->current->data; 
// ... 
free(B); 

這會泄漏一大塊內存，然後將某些內容從您的節點結構中釋放出來。解決這個問題，問題可能會消失。