总是出错，不知道什么原因，，，，，

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

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            string str1 = "C#编程宝典";
            string str2=str1.PadLeft(str1.Length+1 ,'<<');
            string str3 = str2.PadRight(str2.Length+1,' >>');
            Console.WriteLine("填充字符串之前:"+str1);
            Console.WriteLine("填充字符串之前:"+str3);
            Console.ReadLine();
        }
    }
}