C # calculates the day of the week based on the year, month, and day.

Sometimes, you may want to calculate the day of the week based on a certain date in ASP. NET. The followingCodeThis computation can be performed.
(There are a lot of sample code on the Internet, but I have read a lot and it is wrong. They were all reproduced and circulated. I am here to make corrections. Haha .)

String caculateweekday (INT y, int M, int D)
{
If (M = 1) {M = 13; y --;}
If (M = 2) {M = 14; y --;}
Int week = (D + 2 * m + 3 * (m + 1)/5 + Y/4-y/100 + Y/400) % 7 + 1;
String weekstr = "";
Switch (week)
{
Case 1: weekstr = "Monday"; break;
Case 2: weekstr = "Tuesday"; break;
Case 3: weekstr = "Wednesday"; break;
Case 4: weekstr = "Thursday"; break;
Case 5: weekstr = "Friday"; break;
Case 6: weekstr = "Saturday"; break;
Case 7: weekstr = "Sunday"; break;
}

Return weekstr;
}
Private void button#click (Object sender, system. eventargs E)
{
Int year = int. parse (textbox1.text );
Int month = int. parse (textbox2.text );
Int day = int. parse (textbox3.text );
Label1.text = caculateweekday (year, month, day );
}

The code is very simple and does not require much explanation. You can understand it at a glance. If it is applied to reality, it is best to check the validity of textbox to prevent illegal data input; or change textbox to dropdownlist. Someone may ask, is there a function in C? Of course. Dayofweek is the function that returns the day of the week. Now that we have written it here, let's give a sample code. As follows:

System. datetime newdate = new datetime (November 1, 11 );
Response. Write (newdate. dayofweek );

Other Instructions: Calculate the day of the weekAlgorithmThere are also the cailer formula, and some improved formulas based on the kempilsen formula and the cailer formula.