用C语言构建HashMap的问题

发布于 2025-01-10 18:16:20 字数 1489 浏览 0 评论 0原文

当我尝试使用 C 构建 hashMap 时，我遇到了问题。我的目标是构建一个附加了链表数组的 hashMap。

我现在正在研究插入元素功能，这是奇怪的部分。我希望在开头插入一个newNode。当我使用临时节点头来存储此链表的“头”并尝试插入时，它失败并且没有值插入。但是如果我直接将头更改为“_hashmap->arrayOfLists[bucket]”，那么它就可以工作..我不知道为什么，我认为有一个临时节点应该可以工作..任何人都可以帮忙解决这个问题吗？谢谢！

typedef 结构对{ 字符*键；字符*值； }pair_t；
typedef 结构节点{ 结构节点*下一个； pair_t* kv;}node_t;

[原始有问题的代码]

void hashmap_insert（hashmap_t* _hashmap，char* 键，char* 值）{

pair_t* newPair = (pair_t*)malloc(sizeof(pair_t));
 newPair->key = (char*)malloc(strlen(key) * sizeof(char)+1);
 newPair->value = (char*)malloc(strlen(value) * sizeof(char)+1);

 strcpy(newPair->key, key); //将输入键复制到malloc空间中。
 strcpy(newPair->value, value); //将输入值复制到malloc空间中。

 //创建一个要插入的newNode。
 node_t* newNode = (node_t*)malloc(sizeof(node_t));
 newNode->kv = newPair;
 newNode->next = NULL;


 unsigned int Bucket = _hashmap->hashFunction(key, _hashmap->buckets);

 node_t* head = _hashmap->arrayOfLists[bucket];

 // 如果桶是空的
  如果（头== NULL）{
      头=新节点；
  } else {//在前面插入newNode。
     newNode->next = head;
      头=新节点；
  }

}

【有效的代码】

 if(_hashmap->arrayOfLists[bucket] == NULL) {
     _hashmap->arrayOfLists[bucket] = newNode;
 } 别的 {
     newNode->next = _hashmap->arrayOfLists[bucket];
     _hashmap->arrayOfLists[bucket] = newNode;
 }

原文

I've encountered problems when I'm trying to build a hashMap using C. My goal is to build a hashMap with an array of linkedlist appended.

I'm now working on the insert element function, and here is the strange part. I hope to insert a newNode at the beginning. When I use a temp node head to store the "head" of this linkedlist and try to insert, it fails with no value insert. But if I change the head directly to "_hashmap->arrayOfLists[bucket]", then it works.. I do not know why and I think having a temp node should work.. Anyone can help with this? Thanks!

typedef struct pair{
char* key;
char* value; }pair_t;
typedef struct node{
struct node* next;
pair_t* kv;}node_t;

[Original problematic code]

void hashmap_insert (hashmap_t* _hashmap, char* key, char* value){

 pair_t* newPair = (pair_t*)malloc(sizeof(pair_t));
 newPair->key = (char*)malloc(strlen(key) * sizeof(char)+1);
 newPair->value = (char*)malloc(strlen(value) * sizeof(char)+1);

 strcpy(newPair->key, key); //copy the input key into the malloc space.
 strcpy(newPair->value, value); //copy the input value into the malloc space.

 //create a newNode that is to be inserted.
 node_t* newNode = (node_t*)malloc(sizeof(node_t));
 newNode->kv = newPair;
 newNode->next = NULL;


 unsigned int bucket = _hashmap->hashFunction(key, _hashmap->buckets);

 node_t* head = _hashmap->arrayOfLists[bucket];

 // if the bucket is empty
  if(head == NULL) {
      head = newNode;
  } else {//insert the newNode at the front.
     newNode->next = head;
      head = newNode;
  }

}

【The code that works]

 if(_hashmap->arrayOfLists[bucket] == NULL) {
     _hashmap->arrayOfLists[bucket] = newNode;
 } else {
     newNode->next = _hashmap->arrayOfLists[bucket];
     _hashmap->arrayOfLists[bucket] = newNode;
 }

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