14.字符串hash寻找第一个只出现一次的字符

 //char 0-255一共256个
 char getonebyhash(char *str)
 {
     if (str == NULL)
     {
         return '\0';
     }
     char ch = '\0';
     //哈希表设置为0
     int hashtable[] = {  };
     //依次获取
     char *phash = str;
 
     //遍历循环字符串数据存放在hash表
     while (*phash != '\0')
     {
         hashtable[*phash]++;
         phash++;
     }
 
     //备份首地址，寻找到第一个值为1的字符
     phash = str;
     while (*phash != '\0')
     {
         if (hashtable[*phash] == )
         {
             ch = *phash;
             break;
         }
         phash++;
     }
     return ch;
 
 }