hash函数

#include<iostream>
#include<stdlib.h>
#include<stdio.h>
#include<string.h>
using namespace std;
char *key[32]= {"auto","break","case","char","const",
                "continue","default","do","double",
                "else","enum","extern",
                "float","for","goto","if","int","long",
                "register", "return", "short",
                "signed","sizeof","static", "struct","switch",
                "typedef","union","unsigned",
                "void","volatile","while"
               };

    int index[32];
    char *HASH[253];
int  hash(char *string)
{
    int i=1;
    int ix = 0;
    for(; *string; string++)
    {
        ix =ix + i*(*string);
        i++;
    }
    ix = ix%253;
    return ix;
};
void create()
{
     int i;
    for(i=0; i<=252; i++)
    {
        HASH[i]="";
    }
    for(i=0; i<32; i++)
    {
        index[i] = hash(key[i]);
        HASH[index[i]] = key[i];
    }

}
int findkey(char * str)
{

    if(strcmp(str,HASH[hash(str)])!=0)
        return 0;
    else
        return 1;
};

int main()
{
    cout<<"关键字的哈希值为:"<<endl;
    int i;
    for(i=0; i<32; i++)
    {
        cout<<hash(key[i])<<"\t";
        if(i!=0&&i%5==0)
            cout<<endl;
    }
    cout<<endl;

    char string[20]= {0};
    create();
    int choice;
     cout<<"请输入你的选择:1,查找关键字；,-1退出查找:"<<endl;
    cin>>choice;
    while(choice!=-1)
    {


        if(choice == 1)
        {
            cout<<"请输入你要查找的关键字:"<<endl;
            cin>>string;

            if(findkey(string))
                cout<<"你所输入的字符串是关键字"<<endl;
            else
               {
                   cout<<"你所输入的字符串不是关键字"<<endl;
                   cout<<"请输入你的选择:1,查找关键字；,退出查找:"<<endl;
               }

        }
        cin>>choice;
    }

    return 0;
}