Question

当我通过“冰”时，这应该返回451,845,518,507但是它返回873,952,427可以有人告诉我为什么吗？（MAX_STR_SIZE = 501）

unsigned long hash_code(const char *str){
  char temp[MAX_STR_SIZE]="";
  unsigned long multiplied;
  if(str == NULL){
    return SUCCESS;
  }
  else if(strlen(str)==0 || str==""){
    return SUCCESS;
  }
  else{

      strncpy(temp,str, strlen(str)-1);
      temp[strlen(str)-1]=0;


      multiplied = (hash_code(temp)*65599 + (int) str[strlen(str)-1]);
      return multiplied;
  }
}

Answer 1

unsigned long在您的计算机上只有32位。需要更广泛的类型451,845,518,507

451,845,518,507 mod pow(2,32) --> 873,952,427

Answer 2

这是固定代码：

#include <stdio.h>
#include <string.h>

#define MAX_STR_SIZE 501

unsigned long long hash_code(const char *str){
    char temp[MAX_STR_SIZE] = "";
    unsigned long long hash;
    if(str == NULL ||  strlen(str) == 0 || *str == '\0'){
        return 0;
    }
    else{
        strncpy(temp, str, strlen(str) - 1);
        hash = hash_code(temp) * 65599 + str[strlen(str) - 1];
        return hash;
    }
}

int main(void)
{
    char str[] = "ice";
    unsigned long long hash;
    hash = hash_code(str);
    printf("%llu", hash);
    return 0;
}

您需要unsigned long long来包含451,845,518,507。

递归哈希码？

2 个答案: