c - 访问返回的二叉树的内容时出现问题

Question

我正在构建一个二叉树 BusTree* BusTreeHead，然后尝试将其分配给其中包含 BusTree* Bushead 的结构，并且它正确分配了它，但是当我尝试访问二叉搜索树的内容时，特别是name、addressOffset 和 reviewOffset，在包装程序的函数之外，我收到诸如此类的错误，但我无法弄清楚原因。感谢您抽出时间。

下面是我的 .c 文件的代码

#include "answer10.h"

#include<stdio.h>
#include<stdlib.h>
#include<string.h>

typedef struct BusList_t{
   int id;
   long int addressOffset;
   long int reviewOffset;
   struct BusList_t* next;
}BusList;


typedef struct BusTree_t{
  char* name;
  BusList* locations;
  struct BusTree_t* left;
  struct BusTree_t* right;
}BusTree;

struct YelpDataBST{
  const char* business;
  const char* reviews;
  BusTree* Bushead;
};

struct YelpDataBST* create_business_bst(const char* businesses_path, const char* reviews_path){

  if(fopen(businesses_path,"r") == NULL || fopen(reviews_path,"r") == NULL)
    return NULL;
  FILE* fp_bp = fopen(businesses_path, "r");
  FILE* fp_rp = fopen(reviews_path, "r");

  struct YelpDataBST* yelp = malloc(sizeof(struct YelpDataBST));

  int ID = -1;
  int tempID;
  int tempID2;
  int end;
  long int addressOffset = -1;
  long int reviewOffset = 0;
  char line[2000];
  char line2[2000];
  char* token;
  char token2[2000];
  char name[2000];
  char state[2000];
  char zip_code[2000];
  char address[2000];
  int len;

  BusList* busListHead = NULL;
  BusTree* busTreeNode = NULL;
  BusTree* busTreeHead = NULL;
   fseek(fp_bp,0, SEEK_END);
   end = ftell(fp_bp);
   ID = 0;
   tempID = 0;
   fgets(line,2000,fp_rp);
   fgets(line2,2000,fp_bp);
   fseek(fp_rp,0, SEEK_SET);
   fseek(fp_bp,0,SEEK_SET);
   int ct = 0;
   while(!feof(fp_rp)){
     if(addressOffset == -1){
    sscanf(line2, "%d\t%[^\t]", &ID, name);
     }
     len = strlen(line);
     sscanf(line, "%d", &tempID);
     if(ct == 0){
       tempID = 1;
       ct++;
     }
     if((ID != tempID || (ID < 0)) && tempID != 0){
       if(tempID == 1)
      tempID = 0;
    sscanf(line2, "\t%d\t%[^\t]", &tempID2, token2);
    if(token2 != NULL){
      if(name != NULL)
        if(strcmp(token2, name) == 0){
          fgets(line2, 2000,fp_bp);
          sscanf(line2, "\t%d\t%[^\t]", &tempID2, token2);
        }
      strcpy(name, token2);
    }
    reviewOffset = ftell(fp_rp);
    if(tempID != 0)
      reviewOffset -= len;
    ID = tempID;//atoi(token);
    if(addressOffset == -1){
      addressOffset = 0;
      fgets(line2, 2000,fp_bp);
    }
    if(addressOffset != end){
      busTreeNode = BusTree_create(name, busListHead, addressOffset, reviewOffset, ID);
      busTreeHead = BusTree_insert(busTreeHead, busTreeNode); //replace with create node for tree
    }
    if(addressOffset != -1)
      addressOffset = ftell(fp_bp);
    fgets(line2,2000,fp_bp);
      }
      fgets(line,2000,fp_rp);

}   
  yelp->Bushead = busTreeHead;
  yelp->business = businesses_path;
  yelp->reviews = reviews_path;
  BusTree_print(yelp->Bushead);
  BusTree_destroy(busTreeHead);
  fclose(fp_bp);
  fclose(fp_rp);
  return yelp; 
}

BusList* BusNode_create(long int addressOffset, long int reviewOffset, int id){
  BusList* loc = malloc(sizeof(BusList));
  loc->id = id;
  loc->addressOffset = addressOffset;
  loc->reviewOffset = reviewOffset;
  loc->next = NULL;
  return loc;
}


BusList* BusNode_insert(BusList* head, long int addressOffset, long int reviewOffset, int id){
 if(head == NULL)
   return BusNode_create(addressOffset, reviewOffset, id);
 if(BusNode_create(addressOffset, reviewOffset, id) == NULL)
   return head;
 BusList* newNode = BusNode_create(addressOffset, reviewOffset, id);
 newNode->next = head;
 return newNode;
}


void BusList_destroy(BusList* head){
  while(head != NULL){
    BusList* next = head->next;
    free(head);
    head = next;
  }
}

void BusList_print(BusList* head){

  while(head != NULL){
    printf("addressOffset: %ld  reviewOffset: %ld\n",head->addressOffset, head->reviewOffset);
    head = head->next;
  }
} 

//Business Tree of Business Linked Lists

BusTree* BusTree_create(const char* name, BusList* busListHead, long int addressOffset, long int reviewOffset, int id){
  BusTree* node = malloc(sizeof(BusTree));
  node->name = strdup(name);
  node->locations = BusNode_insert(busListHead, addressOffset, reviewOffset, id);
  node->left = NULL;
  node->right = NULL;
  return node;
}

BusTree* BusTree_insert(BusTree* root, BusTree* node){
  if(root == NULL)
    return node;
  if(node == NULL)
    return root;

  int cmp = strcmp(node->name, root->name);

  if(cmp < 0){
    root->left = BusTree_insert(root->left, node);
  }
  else if(cmp> 0){
    root->right = BusTree_insert(root->right, node);
  }
  else{
    root->locations = BusNode_insert(root->locations, node->locations->addressOffset, node->locations->reviewOffset, node->locations->id);
  }
  return root;
}

void BusTree_destroy(BusTree* root){
  if(root == NULL){
    free(root);
    return;
  }
  BusTree_destroy(root->left);
  BusTree_destroy(root->right);
  BusList_destroy(root->locations);
  free(root->name);
  free(root);
}

Answer 1

您正在编写 C，而不是 C++，因此没有复制构造函数。当你这样做时:

yelp->Bushead = busTreeHead;

您只需使 yelp->Bushead 指向与 busTreeHead 相同的内存即可；不执行深复制。此后不久，当您这样做时:

BusTree_destroy(busTreeHead);

您正在释放 yelp->Bushead 指向的内存，因为 busTreeHead 指向同一内存。

由于此例程的目的是返回包含您已构建的 BusTree* Bushead 的 YelpDataBST，因此似乎调用 BusTree_destroy(busTreeHead) 应该简单地删除。

顺便说一句，我相信您打开文件两次:

if(fopen(businesses_path,"r") == NULL || fopen(reviews_path,"r") == NULL)
    return NULL;
fp_bp = fopen(businesses_path, "r");
fp_rp = fopen(reviews_path, "r");

您应该只打开它们一次。