C#获取本周五日期字符串

 using System;
 using System.Collections.Generic;
 using System.Globalization;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;

 namespace Demo
 {
     class Program
     {
         static void Main(string[] args)
         {
             string FriStr = GetDateOfDayInWeek(DateTime.Now, DayOfWeek.Friday);
             Console.WriteLine(FriStr);
             Console.ReadKey();
         }

         static string GetDateOfDayInWeek(DateTime dt, DayOfWeek dw)
         {
             DateTime date = dt.AddDays(dw - dt.DayOfWeek);
             //具体显示格式参见:https://msdn.microsoft.com/zh-cn/library/8tfzyc64.aspx
             return date.ToString("dd MMMM yyyy", DateTimeFormatInfo.InvariantInfo);
         }
     }
 }

更多日期显示格式参照：http://www.cnblogs.com/ATree/archive/2010/06/06/CSharp-DateTime-Tostring-LongDatePattern.html