c#从特定日期提取星期几

using System;
using System.Collections.Generic;
using System.Text;

namespace Proj2_1
{
class Program
{
struct Stud
{
public int studn;
public string name;
public string bday;
}
static void Main(string[] args)
{
Stud s1, s2;
s1.studn = 101;
s1.name = "郭靖";
s1.bday ="1991,1,1";
Console.WriteLine("学号:{0},姓名:{1},出生日期{2}",s1.studn,s1.name,s1.bday);
s2.studn = 102;
s2.name = "黄蓉";
s2.bday ="1991,2,2";
Console.WriteLine("学号:{0},姓名:{1},出生日期{2}",s2.studn,s2.name,s2.bday);
Console.WriteLine(DateTime.Now.DayOfWeek.ToString(s2.bday ));
}
}
}

DateTime.Now.DayOfWeek;
new DateTime().DayOfWeek;
DayOfWeek是一个星期几的枚举

DateTime birth = new DateTime(1991, 2, 2);
DayOfWeek week = birth.DayOfWeek;

用asc来判断 string sss="dfjhsa2324"; string str=""; for(int i=0;i<sss.length;i++) { if(isnumeric(sss[i].tostring())) { str=str+sss[i].tostring(); } } response.write("这些数为整数："+str); private bool isnumeric(string str)//判断是否为证整数 { system.text.asciiencoding ascii = new system.text.asciiencoding(); byte[] bytestr = ascii.getbytes(str); foreach (byte c in bytestr) { if (c < 48 || c > 57) { return false; } } return true; } 除了这个。你也可以考虑用正则表达式