C# object initializer

using System;
using System.Collections.Generic;
using System.Linq;using System.Text; 
namespace 对象初始化器
{    
class Program    
{        
static void Main(string[] args)        
{            
//第二种初始化            
var s1 = new student("张三",23);            
Console.WriteLine(s1.ToString());             
//第一种初始化            
var s2 = new student { name = "李四", age = 34 };           
Console.WriteLine(s2.ToString());             
//第三种            
var s3 = new student("王五",30) { ID=1};        
}    
}    
public class student    
{        
public string name { set; get; }        
public int age { set; get; }        
public int ID { set;get;}         
//第一种构造函数        
public student()        
{        
}         
//第二种构造函数        
public student(string Name, int Age)        
{            
name = Name;            
age = Age;        
}        
//方法重载        
public override string ToString()        
{            
return name + ":" + age.ToString();         
}    
}
}