c# - How to get the first day of a month using a given date

DateTime get beginning of month
The following asp.net c# example code demonstrate us how can we get the first day of a month from a given DateTime object programmatically at run time in an asp.net application. By default, .net framework's DateTime Class has no method or property to get first day of a month. So we need to follow some techniques to get it.

First, we store the specified date to a DateTime variable. Next, we initialize a new DateTime object from the given DateTime object's Year part, Month part and First day such as 2014/12/1 (DateTime.Year/DateTime.Month/1). We only take the year and month part from the given DateTime object and create a new date from it where day number is 1. Finally, we get the first day of month/beginning of a month from a specified date.

<%@ Page Language="C#" AutoEventWireup="true"%>  
<!DOCTYPE html>      
<script runat="server">
    protected void Button1_Click(object sender, System.EventArgs e)
        //initialize a datetime variable with today
        DateTime today = DateTime.Today;

        //create a datetime object with first day of current month
        DateTime firstDayOfMonth = new DateTime(today.Year,today.Month,1);
        Label1.Text = "Today : " + today.ToLongDateString();
        Label1.Text += "<br />first day of month : ";
        Label1.Text += firstDayOfMonth.ToLongDateString();
<html xmlns="http://www.w3.org/1999/xhtml">      
<head id="Head1" runat="server">      
    <title>c# example - datetime beginning of month</title>      
    <form id="form1" runat="server">      
        <h2 style="color:MidnightBlue; font-style:italic;">      
            c# example - datetime beginning of month
        <hr width="550" align="left" color="Gainsboro" />      
            Font-Names="Comic Sans MS"
        <br /><br />    
            Text="get first day of month"      
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