C#类型转换

string str1 = Console.ReadLine();
string str2 = Console.ReadLine();

int x = Convert.ToInt32(str1);
int y = Convert.ToInt32(str2);

int result = x + y;
Console.WriteLine(result);
Console.ReadKey();

隐式类型转换（implicit）

• 不丢失精度的转换

int x = int.MaxValue;
long y = x;    

不丢失精度的隐式类型转换

• 子类向父类的转换

using System;

namespace Test
{
    class User
    {
        public void Login()
        {
            Console.Write("user login\n");
        }
    }
    class Member : User
    {
        public void Profile()
        {
            Console.WriteLine("member profile\n");
        }
    }
    class GuildMember : Member
    {
        public void JoinGuild()
        {
            Console.WriteLine("guild member join\n");
        }
    }
    class Program
    {
        static void Main(string[] args)
        {

            GuildMember gm = new GuildMember();
            Member m = gm;
            User u = m;
            u.Login();

            m.Login();
            m.Profile();

            gm.Login();
            gm.Profile();
            gm.JoinGuild();

            Console.ReadKey();
        }
    }
}

• 装箱（boxing）

显示类型转换（explicit）

• 可能丢失精度，甚至发生错误，即cast。

ushort maxval = ushort.MaxValue;

uint x = 65536;
ushort y = (ushort)x;//0

显示类型转换

• 拆箱（unboxing）
• 建议使用Convert工具类
• ToString()与数据类型的Parse/TryParse方法
  Parse只能解析格式正确的数据

自定义类型转换操作符

using System;

namespace Test
{          
    class User
    {
        public int age;
        public static explicit operator Member(User user)
        {
            Member member = new Member();
            member.age = user.age;
            return member;
        }
    }
    class Member
    {
        public int age = 1000;
    }
    class Program
    {
        static void Main(string[] args)
        {
            User u = new User();
            Member m = (Member)u;
            Console.WriteLine(m.age);

            Console.ReadKey();
        }
    }
}