explicit 和 implicit 的用法

explicit 和 implicit 属于转换运算符，如用这两者可以让我们自定义的类型支持相互交换

explicti 表示显式转换，如从 A -> B 必须进行强制类型转换（B = (B)A）

implicit 表示隐式转换，如从 B -> A 只需直接赋值（A = B）

隐式转换可以让我们的代码看上去更漂亮、更简洁易懂，所以最好多使用 implicit 运算符。不过！如果对象本身在转换时会损失一些信息（如精度），那么我们只能使用 explicit 运算符，以便在编译期就能警告客户调用端

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

namespace implicit_explicit
{
class Program
    {
static void Main(string[] args)
        {  
            TesImplicit t = new TesImplicit();
            User u = new User() { Id = 1, Name = "lichaoqiang" };
            Console.WriteLine("隐式转换-----------------------------------------------------------------");
            Customer c = u;
            Console.WriteLine(c.CustomerId+"="+c.CustomerName);


#region 2>显示转换
            Customer customer = u;
            VIP v = (VIP)customer;
            Console.WriteLine("显示转换-----------------------------------------------------------------");
            t.GetVIPInfo(v);
#endregion

            Console.ReadLine();
        }
    }


/// <summary>
/// test case
/// </summary>
public class TesImplicit
    {
/// <summary>
/// get the customer infomation
/// </summary>
/// <param name="customer"></param>
public void GetCusterInfo(Customer customer)
        {
            Console.WriteLine("Customer:" + customer.CustomerName);
        }

public void GetVIPInfo(VIP vip)
        {
            Console.WriteLine("VIP:" + vip.VName);
        }
    }
/// <summary>
/// 
/// </summary>
public class User
    {
/// <summary>
/// 
/// </summary>
public long Id { get; set; }

/// <summary>
/// 
/// </summary>
public string Name { get; set; }

/// <summary>
/// 隐式转换
/// </summary>
/// <param name="u"></param>
/// <returns></returns>
public static implicit operator Customer(User u)
        {
return new Customer()
            {
                CustomerId = u.Id,
                CustomerName = u.Name
            };
        }

    }

/// <summary>
/// 
/// </summary>
public class Customer
    {
/// <summary>
/// 
/// </summary>
public long CustomerId { get; set; }

/// <summary>
/// 
/// </summary>
public string CustomerName { get; set; }

/// <summary>
/// 显示转换
/// </summary>
/// <param name="c"></param>
/// <returns></returns>
public static explicit operator VIP(Customer c)
        {
return new VIP()
            {
                VID = c.CustomerId,
                VName = c.CustomerName
            };
        }
    }

/// <summary>
/// 
/// </summary>
public class VIP
    {
/// <summary>
/// 
/// </summary>
public long VID { get; set; }

/// <summary>
/// 
/// </summary>
public string VName { get; set; }
    }
}