HashTable的C++实现

由哈希表的定义，采用C++完成了一个学生成绩存储系统，分析过程如下：

由于哈希表是按KEY值存储，我们假设KEY值为一个字符串。hash算法为字符串的前两位大写字母所对应的数字对一个质数的模运算。

int Hash(KeyType c)
{
    int n = c[] - 'A'+c[]-'A'+;
    return n % Mod;
}

哈希表的类定义如下

class HashTable
{
public:
//    HashTable();
    HashTable(int len);
    ~HashTable();
    bool SearchHash(KeyType K, int &p, int &c,int &s);
    bool InsertHash(ElemType e);
private:
    ElemType * elem;
    int count;
    int sizeindex;
};

搜索函数SearchHash

bool HashTable::SearchHash(KeyType K, int &p, int &c,int &s)
{
    c = ;
    p = Hash(K);
    std::string NULLKey = "None";
    while (this->elem[p].key != NULLKey && K != this->elem[p].key)
    {
        p++;
        c++;//冲突次数++
    }
//    cout << "after,p = " << p << endl;
    if (K == this->elem[p].key)
    {
        s = elem[p].score;
        return true;
    }
    else
        return false;
}

插入函数InsertHash

bool HashTable::InsertHash(ElemType e)
{
    int c = ;//c为冲突次数
    int p,s;
    if (SearchHash(e.key, p, c,s))
        return false;
    else if (c < Hashsize[this->sizeindex] / )
    {
        this->elem[p] = e;
        this->count++;
        return true;
    }
    else
    {
        HashTable();
        return false;
    }
}

任务源代码如下：

哈希表元素类

 //ElemType.h

 #ifndef ELEMTYPE_H
 #define ELEMTYPE_H
 #include<string>
 typedef std::string KeyType;
 class ElemType
 {
 public:
     KeyType key;
     int score;
 };
 #endif

哈希表类

 //HashTable.h

 #ifndef HASHTABLE_H
 #define HASHTABLE_H
 #include"ElemType.h"

 class HashTable
 {
 public:
 //    HashTable();
     HashTable(int len);
     ~HashTable();
     bool SearchHash(KeyType K, int &p, int &c,int &s);
     bool InsertHash(ElemType e);
 private:
     ElemType * elem;
     int count;
     int sizeindex;
 };

 #endif

哈希表的操作函数

 //HashTable.cpp

 #include"HashTable.h"
 #include<iostream>
 using namespace std;
 const int Mod = ;//质数模
 int Hashsize[] = { ,,, };
 int Hash(KeyType c)
 {
     int n = c[] - 'A'+c[]-'A'+;
     return n % Mod;
 }

 HashTable::HashTable(int len=)
 {
     elem = new ElemType[len];
     for (int i = ; i < len; i++)
     {
         elem[i].key = "None";
     }
     count = ;
     sizeindex = ;
 }

 HashTable::~HashTable()
 {
     delete[] elem;
     count = ;
     sizeindex = ;
 }

 bool HashTable::SearchHash(KeyType K, int &p, int &c,int &s)
 {
     c = ;
     p = Hash(K);
     std::string NULLKey = "None";
     while (this->elem[p].key != NULLKey && K != this->elem[p].key)
     {
         p++;
         c++;//冲突次数++
     }
 //    cout << "after,p = " << p << endl;
     if (K == this->elem[p].key)
     {
         s = elem[p].score;
         return true;
     }
     else
         return false;
 }

 bool HashTable::InsertHash(ElemType e)
 {
     int c = ;//c为冲突次数
     int p,s;
     if (SearchHash(e.key, p, c,s))
         return false;
     else if (c < Hashsize[this->sizeindex] / )
     {
         this->elem[p] = e;
         this->count++;
         return true;
     }
     else
     {
         HashTable();
         return false;
     }
 }

信息存储的实现

 //Main.cpp

 #include"HashTable.h"
 #include<iostream>
 using namespace std;
 int main()
 {
     HashTable* H = new HashTable();
     ElemType e;
     int p,c;
     int i=;
     KeyType k;
     int score;
     while (i != )
     {
         switch (i)
         {
         case :
             cout << "***______HashTable_____***" << endl;
             cout << "***___1.Display menu___***" << endl;
             cout << "***___2.Insert_________***" << endl;
             cout << "***___3.Search_________***" << endl;
             cout << "***___0.Exit___________***" << endl;
             break;
         case :
             cout << "input name with A~Z: ";
             cin >> k;
             e.key = k;
             cout << "input score with number: ";
             cin >> score;
             e.score = score;
             H->InsertHash(e);
             break;
         case :
             cout << "input name with A~Z: ";
             cin >> k;
             if (H->SearchHash(k, p, c, score))
             {
                 cout << k << "'s score is " << score << endl;;
             }
             else
                 cout << "can't found" << endl;
             break;

         }
         cout << "输入选项：";
         cin >> i;
     }
     system("pause");
     return ;
 }

效果如下

***______HashTable_____***
***___1.Display menu___***
***___2.Insert_________***
***___3.Search_________***
***___0.Exit___________***
输入选项：
input name with A~Z: DSG
input score with number:
输入选项：
input name with A~Z: QWER
input score with number:
输入选项：
input name with A~Z: DSG
DSG's score is 99
输入选项：
input name with A~Z: OOP
input score with number:
输入选项：
input name with A~Z: QWER
QWER's score is 70
输入选项：
input name with A~Z: OOP
OOP's score is 100
输入选项：
请按任意键继续. . .