如何獲得月和本月的最後一天的第一天使用日期時間在C＃

Question

using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Web; 
using System.Web.UI; 
using System.Web.UI.WebControls; 

public partial class calenderdisp : System.Web.UI.Page 
{ 
    DateTime dt = DateTime.Now; 
    protected void Page_Load(object sender, EventArgs e) 

    { 
     if (!IsPostBack) 
     { 
      if (ddlweeklist.SelectedItem.Text == "Today") 
      { 
       txtstart.Text = DateTime.Now.ToString("dd/MM/yyyy"); 

       Txtend.Text = DateTime.Today.ToString("dd/MM/yyyy"); 




      } 
     } 


    } 
    protected void ddlweeklist_SelectedIndexChanged(object sender, EventArgs e) 
    { 
     if (ddlweeklist.SelectedItem.Text == "This Week") 
     { 
      int st = DayOfWeek.Sunday - dt.DayOfWeek; 
      int en = DayOfWeek.Saturday - dt.DayOfWeek; 
      txtstart.Text = dt.AddDays(st).ToString("dd/MM/yyyy"); 
      Txtend.Text = dt.AddDays(en).ToString("dd/MM/yyyy"); 

     } 

     if (ddlweeklist.SelectedItem.Text == "Next Week") 
     { 
      DateTime dt1 = dt.AddDays(7); 
      int st = DayOfWeek.Sunday - dt1.DayOfWeek; 
      int en = DayOfWeek.Saturday - dt1.DayOfWeek; 
      txtstart.Text = dt1.AddDays(st).ToString("dd/MM/yyyy"); 
      Txtend.Text = dt1.AddDays(en).ToString("dd/MM/yyyy"); 

     } 

     if (ddlweeklist.SelectedItem.Text == "Last Week") 
     { 
      DateTime dt2 = dt.AddDays(-7); 
      int st = DayOfWeek.Sunday - dt2.DayOfWeek; 
      int en = DayOfWeek.Saturday - dt2.DayOfWeek; 
      txtstart.Text = dt2.AddDays(st).ToString("dd/MM/yyyy"); 
      Txtend.Text = dt2.AddDays(en).ToString("dd/MM/yyyy"); 

     } 

     if (ddlweeklist.SelectedItem.Text == "This Month") 
     { 
      DateTime stmonth = new DateTime(dt.Year, dt.Month, 1); 
     DateTime enmnth = new DateTime(dt.Year, dt.Month, DateTime.DaysInMonth(dt.Year, dt.Month)); 
     txtstart.Text = stmonth.ToString("dd/MM/yyyy"); 
     Txtend.Text = enmnth.ToString("dd/MM/yyyy"); 
     txtnodm.Text = DateTime.DaysInMonth(dt.Year, dt.Month).ToString(); 
     Isleap(); 
     } 
    } 
} 

現在得到的答案...感謝ü.........但如何這可以使用Java腳本來完成因爲我是非常有興趣去學習它，請您給點建議這個代碼寫在JavaScript

，我會很高興如果u讓我知道了標準書應遵循學習java腳本

Answer 1

var d = DateTime.Today; 
// Start 
d.AddDays(-d.Day+1); 
// End 
d.AddMonths(1).AddDays(-d.Day).Dump(); 

Answer 2

使用DateTime構造函數的第一天很容易。最後一天比下個月的第一天少一天。

public static void FirstAndLastDayOfMonth(DateTime date, out DateTime first, out DateTime last) { 
    first = new DateTime(date.Year, date.Month, 1); 
    DateTime nextFirst; 
    if (first.Month == 12) nextFirst = new DateTime(first.Year + 1, 1, 1); 
    else nextFirst = new DateTime(first.Year, first.Month + 1, 1); 
    last = nextFirst.AddDays(-1); 
} 

你也可以通過這種方式得到最後一天：

DateTime today = DateTime.Today; 
DateTime endOfMonth = new DateTime(today.Year, today.Month, DateTime.DaysInMonth(today.Year, today.Month)); 

或：

DateTime today = DateTime.Today; 
DateTime endOfMonth = new DateTime(today.Year, today.Month, 1).AddMonths(1).AddDays(-1); 

這個鏈接也可以幫助你：

http://www.c-sharpcorner.com/UploadFile/scottlysle/FirstAndLastDay10262007135750PM/FirstAndLastDay.aspx

Answer 3

要獲得星期一的第一天日：

String day = System.DateTime.Now.DayOfWeek.ToString(); 
      int date = System.DateTime.Now.Day; 
      String fdm = System.DateTime.Now.AddDays(-Convert.ToDouble(date - 1)).DayOfWeek.ToString(); 

要獲得每月的最後一天：

var now = DateTime.Now; 
      var startOfMonth = new DateTime(now.Year, now.Month, 1); 
      var DaysInMonth = DateTime.DaysInMonth(now.Year, now.Month); 
      var lastDay = new DateTime(now.Year, now.Month, DaysInMonth); 
      string lastday = lastDay.DayOfWeek.ToString(); 

Answer 4

請與下面的代碼片段嘗試。

DateTime dt = DateTime.Now; //Your Date 

DateTime start = new DateTime(dt.Year, dt.Month, 1); //First Date of the month 
DateTime end = start.AddMonths(1).AddDays(-1); //Last Date of the month 

string startDay = start.DayOfWeek.ToString(); //First weekday of the month 
string endDay = end.DayOfWeek.ToString(); //Last weekday of the month 

Answer 5

DateTime dt = DateTime.Now.AddDays(-(DateTime.Now.Day - 1)); 
int lday= DateTime.DaysInMonth(DateTime.Now.Year, DateTime.Now.Month); 
DateTime DTY = new DateTime(DateTime.Now.Year, DateTime.Now.Month, lday); 

MessageBox.Show("First Day :- "+dt.DayOfWeek.ToString()); 
MessageBox.Show("Last Day :-" + DTY.DayOfWeek.ToString());