原创 不需查表的万年星期算法C语言程序源码(菜农自创)

这里介绍一种不用查表的公式：Zeller's Rule

The following formula is named Zeller's Rule after a Reverend Zeller. [x] means the greatest integer that is smaller than or equal to x. You can find this number by just dropping everything after the decimal point. For example, [3.79] is 3. Here's the formula:

f = k + [(13*m-1)/5] + D + [D/4] + [C/4] - 2*C.

（k + [(13*m-1)/5] + D + [D/4] + [C/4] - 2*C）mod 7

k日、m月、D年、C百年。谁会推导这个公式？（不难的）

• k is the day of the month. Let's use January 29, 2064 as an example. For this date, k = 29.
• m is the month number. Months have to be counted specially for Zeller's Rule: March is 1, April is 2, and so on to February, which is 12. (This makes the formula simpler, because on leap years February 29 is counted as the last day of the year.) Because of this rule, January and February are always counted as the 11th and 12th months of the previous year. In our example, m = 11.
• D is the last two digits of the year. Because of the month numbering, D = 63 in our example, even though we are using a date from 2064.
• C stands for century: it's the first two digits of the year. In our case, C = 20.

Now let's substitute our example numbers into the formula.

f = k + [(13*m-1)/5] + D + [D/4] + [C/4] - 2*C
= 29 + [(13*11-1)/5] + 63 + [63/4] + [20/4] - 2*20
= 29 + [28.4] + 63 + [15.75] + [5] - 40
= 29 + 28 + 63 + 15 + 5 - 40
= 100.

Once we have found f, we divide it by 7 and take the remainder (if the remainder is negative, add 7). A remainder of 0 corresponds to Sunday, 1 means Monday, etc. For our example, 100 / 7 = 14, remainder 2, so January 29, 2064 will be a Tuesday.

哈哈~~~那是阿莫站长送个我的自留地~~~

http://www.ouravr.com/bbs/bbs_list.jsp?bbs_id=1033&bbs_page_no=1

实际上这个算法的优点是不查表.

我反常规地"排表"为3月起头,即

3,4,5,6,7,8,9,10,11,12,1,2

而且1,2刚好与5,6表相同,这样就彻底地抛开了表的束缚~~~

用机器语言表述如下:

  if (m <= 2){
    m |= 4;//1月2月同5月六月表
    y--;
  }
这句是"精华"~~~

好东西，收下了。敢问一声“菜农”是OURAVR上的吗？