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  1. #include <stdio.h>
  2.  
  3.  
  4. int Zeller(int year, int month, int day) {
  5.     // 1月, 2月は前年の13月, 14月とする
  6.     if (month == 1 || month == 2) {
  7.         month += 12;
  8.         year -= 1;
  9.     }
  10.  
  11.     int Y = year % 100;     
  12.     int C = year / 100;     
  13.  
  14.     int weekday = ((day + (26 * (month + 1) / 10) + Y + Y / 4 + 5 * C + C / 4) + 5) % 7;
  15.  
  16.     return weekday; 
  17. }
  18.  
  19. int main() {
  20.     int year, month, day;
  21.  
  22.     // 確認
  23.     year = 2020;
  24.     month = 6;
  25.     day = 27;
  26.  
  27.     int weekday = Zeller(year, month, day);
  28.  
  29.     printf("西暦%d年%d月%d日の曜日番号は: %d\n", year, month, day, weekday);
  30.  
  31.     // 入力用
  32.     /*
  33.     printf("西暦年を入力してください: ");
  34.     scanf("%d", &year);
  35.     printf("月を入力してください: ");
  36.     scanf("%d", &month);
  37.     printf("日を入力してください: ");
  38.     scanf("%d", &day);
  39.     printf("曜日番号は: %d\n", Zeller(year, month, day));
  40.     */
  41.  
  42.     return 0;
  43. }
Success #stdin #stdout 0s 5324KB
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西暦2020年6月27日の曜日番号は: 5
https://ideone.com/yFrq1b
language:
C (gcc 8.3)
created:
2 days ago
visibility:
public

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