很简单的c#程序，我不知错在哪里?能不能指点一下阿

Question

using System;
namespace p3_1
{    struct contact
    {
        public string name;
        public int age;
        public string tel;
        public struct address
        {
           public string city;
           public string street;
           public int number;
        }
       struct address m_address;
    }
    public class Stuctsample
    {
        public static void Main()
        {
            struct contact c1;
            c1.name="贝克汉姆";
            c1.age=23;
            c1.tel="不明";
            c1.m_address.city="曼彻斯特";
            c1.m_address.street="老特拉福德";
            c1.m_address.number="7";
             Console.WriteLine (c1.name);
             Console.WriteLine (c1.age);
             Console.WriteLine (c1.tel);
             Console.WriteLine(c1.m_address.city);
             Console.WriteLine(c1.m_address.street);
             Console.WriteLine(c1.m_address.number);
        }
    }
}

Answer 1

一分不给。。不厚道using System;
namespace p3_1
{    struct contact
    {
        public string name;
        public int age;
        public string tel;
        public struct address
        {
           public string city;
           public string street;
           public int number;
        }
         //struct address m_address;
        public address m_address;
    }
    public class Stuctsample
    {
        public static void Main()
{
//  struct contact c1;
   contact c1;
            c1.name="贝克汉姆";
            c1.age=23;
            c1.tel="不明";
            c1.m_address.city="曼彻斯特";
            c1.m_address.street="老特拉福德";
            c1.m_address.number=7;
            Console.WriteLine (c1.name);
            Console.WriteLine (c1.age);
            Console.WriteLine (c1.tel);
            Console.WriteLine(c1.m_address.city);
            Console.WriteLine(c1.m_address.street);
            Console.WriteLine(c1.m_address.number);
Console.ReadLine();
        }
    }
}