Question

我尝试使用Zeller's Congruence编写代码来查找给定日期的星期几，但我没有得到正确的输出。我的代码出了什么问题？

#include <stdio.h>
#include <math.h>
int main()
{
  int h,q,m,k,j,day,month,year;
  printf("Enter the date (dd/mm/yyyy)\n");
  scanf("%i/%i/%i",&day,&month,&year);
  if(month == 1)
  {
    month = 13;
    year--;
  }
  if (month == 2)
  {
    month = 14;
    year--;
  }
  q = day;
  m = month;
  k = year % 100;
  j = year / 100;
  h = q + floor(13/5*(m+1)) + k + floor(k/4) +  floor(j/4) + 5 * j;
  h = h % 7;
  switch(h)
  {
    case 0 : printf("Saturday.\n"); break;
    case 1 : printf("Sunday.\n"); break;
    case 2 : printf("Monday. \n"); break;
    case 3 : printf("Tuesday. \n"); break;
    case 4 : printf("Wednesday. \n"); break;
    case 5 : printf("Thurday. \n"); break;
    case 6 : printf("Friday. \n"); break;
  }
  return 0;
}

Answer 1

这是一个有效的版本：

#include <stdio.h>
#include <math.h>
int main()
{
  int h,q,m,k,j,day,month,year;
  printf("Enter the date (dd/mm/yyyy)\n");
  scanf("%i/%i/%i",&day,&month,&year);
  if(month == 1)
  {
    month = 13;
    year--;
  }
  if (month == 2)
  {
    month = 14;
    year--;
  }
  q = day;
  m = month;
  k = year % 100;
  j = year / 100;
  h = q + 13*(m+1)/5 + k + k/4 + j/4 + 5*j;
  h = h % 7;
  switch(h)
  {
    case 0 : printf("Saturday.\n"); break;
    case 1 : printf("Sunday.\n"); break;
    case 2 : printf("Monday. \n"); break;
    case 3 : printf("Tuesday. \n"); break;
    case 4 : printf("Wednesday. \n"); break;
    case 5 : printf("Thurday. \n"); break;
    case 6 : printf("Friday. \n"); break;
  }
  return 0;
}

Live demo

关键在于h公式：13/5*(m+1)。这是使用整数除法，首先计算13/5，因此结果等同于2*(m+1)。交换5和(m+1)左右，结果将是正确的。

顺便提一下，如果维基文章解释的那样，你需要在1月/ 2月减去年份。

Answer 2

为什么要包括＆＃34; h =年％100＆＃34;和＆＃34; j =年/ 100＆＃34; ?????

#include <stdio.h>
#include <math.h>
int main()
{
  int h,q,m,k,j,day,month,year;
  printf("Enter the date (dd/mm/yyyy)\n");
  scanf("%i/%i/%i",&day,&month,&year);
  if(month == 1)
  {
    month = 13;
    year--;
  }
  if (month == 2)
  {
    month = 14;
    year--;
  }
  q = day;
  m = month;
  k = year % 100;
  j = year / 100;
  h = q + 13*(m+1)/5 + k + k/4 + j/4 + 5*j;
  h = h % 7;
  switch(h)
  {
    case 0 : printf("Saturday.\n"); break;
    case 1 : printf("Sunday.\n"); break;
    case 2 : printf("Monday. \n"); break;
    case 3 : printf("Tuesday. \n"); break;
    case 4 : printf("Wednesday. \n"); break;
    case 5 : printf("Thurday. \n"); break;
    case 6 : printf("Friday. \n"); break;
  }
  return 0;
}

使用Zeller的同余来确定星期几

2 个答案: