简易的hashtable实现

参考他人思路而写,具体可参考：http://blog.csdn.net/anialy/article/details/7620469

#ifndef _HASHTABLE_
#define _HASHTABLE_
#include<iostream>
using namespace std;



template<typename key_type,typename value_type>
struct HashNode{
    key_type key;
    value_type value;
    HashNode* next;
    HashNode(key_type key,value_type value):key(key),value(value),next(NULL){}
    HashNode& operator =(const HashNode& rhs){
        key = rhs.key;
        value = rhs.value;
        next = rhs.next;
        return *this;
    }
    ~HashNode(){}
};

template<typename key_type,typename value_type,typename Func>
class HashTable{
public:
    //enum{TableSize = 100};
    typedef HashNode<key_type,value_type>* pointer;
    HashNode<key_type,value_type>** table;
    unsigned long capacity;
    Func GetKeyValue;
    const value_type _null;
    HashTable(Func func,const value_type& _null);
    ~HashTable();
    void put(const HashNode<key_type,value_type>&);
    value_type del(const key_type& key);
    value_type getValue(const key_type& key);
};

template<typename key_type,typename value_type,typename Func>
HashTable<key_type,value_type,Func>::HashTable(Func func,const value_type& _null):_null(_null){
    GetKeyValue = func;
    capacity = 100000000;
    table = new HashNode<key_type,value_type>*[capacity];
    for(unsigned long i=0;i<capacity;i++)
        table[i]=NULL;
}

template<typename key_type,typename value_type,typename Func>
HashTable<key_type,value_type,Func>::~HashTable(){
    pointer node = NULL;
    for(unsigned long i=0;i<capacity;i++){
        node = table[i];
        while(node!=NULL){
            pointer temp = node;
            node = node->next;
            delete temp;
            temp = NULL;
        }
    }
    delete[] table;
}

template<typename key_type,typename value_type,typename Func>
void HashTable<key_type,value_type,Func>::put(const HashNode<key_type,value_type>& node){
    pointer hashnode=NULL;
    unsigned long index = GetKeyValue(node.key);
    hashnode = table[index];
    if(hashnode == NULL){
        HashNode<key_type,value_type>* temp = new HashNode<key_type,value_type>(node.key,node.value);
        table[index] = temp;
    }else{
        HashNode<key_type,value_type>* temp = new HashNode<key_type,value_type>(node.key,node.value);
        temp->next = hashnode;
        table[index] = temp;
    }
}

template<typename key_type,typename value_type,typename Func>
value_type HashTable<key_type,value_type,Func>::del(const key_type& key){
    unsigned long index = GetKeyValue(key);
    pointer hashnode = table[index];
    pointer pre = NULL;
    if(hashnode==NULL)return _null;
    if(hashnode->key==key){
        table[index] = hashnode->next;
        value_type revalue = hashnode->value;
        delete hashnode;
        table[index]=NULL;
        return revalue;
    }
    while(hashnode->key!=key&&hashnode!=NULL){
        pre = hashnode;
        hashnode = hashnode->next;
    }
    if(hashnode==NULL)return _null;
    pre->next = hashnode->next;
    value_type revalue = hashnode->value;
    delete hashnode;
    return revalue;
}

template<typename key_type,typename value_type,typename Func>
value_type HashTable<key_type,value_type,Func>::getValue(const key_type& key){
    unsigned long index = GetKeyValue(key);
    pointer hashnode = table[index];
    if(hashnode==NULL)return _null;
    while(hashnode->key!=key&&hashnode!=NULL)hashnode = hashnode->next;
    if(hashnode==NULL)return _null;
    return hashnode->value;
}
#endif

以上是头文件；

 #include<iostream>
  #include<time.h>
  #include<string>
  #include<cstdlib>
  #include"hashtable.h"
  using namespace std;
  
  typedef unsigned long (*GetKeyValue)(const string& rhs);
  unsigned long get_key(const string& key){
     unsigned long hash = 0;
     unsigned long  i=0;
     while(i<key.length())
     {
         // equivalent to: hash = 65599*hash + (*str++);
         hash = key[i] + (hash << 6) + (hash << 16) - hash;
         i++;
     }
 
     return (hash & 0x7FFFFFFF)>>8;//右移8位，是因为容易越界访问
 }
  
 int main(){
      
     //传入一个求哈希散列值的方法get_key
     HashTable<string,string,GetKeyValue> hashMap(get_key,"NULL");  
     for(int i = 0;i < 10000;i++){  
         char *ckey = new char[20];  
         char *cvalue = new char[20];  
         ckey = itoa(i,ckey,8);  
         cvalue = itoa(i,cvalue,8);  
         string key(ckey);  
         string value(cvalue);  
         if(i == 67){  
             key = "67";  
             value = "hello hash No.67";  
         }  
         HashNode<string,string> node1(key,value);  
         //插入该节点  
         hashMap.put(node1);  
     }  
     cout << "hashMap.GetValue("100"): " << hashMap.getValue("100") << endl;  
     cout << "hashMap.Delete("67"): " << hashMap.del("67") << endl;  
     cout << "hashMap.GetValue("67"): " << hashMap.getValue("67") << endl;  
     return 0;  
 }