C# 静态构造函数

  static class Program
    {
        static void Main(string[] args)
        {
            Test.TestIns.Flag = Test.TestIns.Flag + 1;
            Console.WriteLine(Test.TestIns.Flag);
            Test.TestIns.Flag = Test.TestIns.Flag + 1;
            Console.WriteLine(Test.TestIns.Flag);
            Test.TestIns.Flag = Test.TestIns.Flag + 1;
            Console.WriteLine(Test.TestIns.Flag);
            Console.ReadKey();
        }
    }

    public class Test
    {
        static Test()
        {
            TestIns = new Test();
        }

        public static Test TestIns;

        public int Flag=0;
    }