【C#】扩展方法的应用

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

namespace ConsoleApplication27
{
class Program
{
static void Main(string[] args)
{
int str1 = 200;
var flag = str1.IsEmail();
Console.WriteLine(flag);
Console.ReadLine();

}

}

public static class ExtensionMethods
{

public static bool IsEmail( this int str)
{
return true;
}

}
}