DateTime - FirstDayOfWeek

A DateTime extension method that first day of week.

Try it

public static void Main()
{
    DateTime date = DateTime.Now;
	
	Console.WriteLine("Original DateTime                    : {0}", date.ToFullDateTimeString());

    // C# Extension Method: DateTime - FirstDayOfWeek
	DateTime endOfDay = date.FirstDayOfWeek();
	
	Console.WriteLine("DateTime after calling FirstDayOfWeek: {0}", endOfDay.ToFullDateTimeString());
}

View Source
using System;

public static partial class Extensions
{
    /// <summary>
    ///     A DateTime extension method that first day of week.
    /// </summary>
    /// <param name="this">The @this to act on.</param>
    /// <returns>A DateTime.</returns>
    public static DateTime FirstDayOfWeek(this DateTime @this)
    {
        return new DateTime(@this.Year, @this.Month, @this.Day).AddDays(-(int) @this.DayOfWeek);
    }
}