c# enum用法
作者:互联网
enum 关键字用于声明枚举,即一种由一组称为枚举数列表的命名常数组成的独特类型。每种枚举类型都有基础类型,该类型可以是除char 以外的任何整型。即:
(byte, sbyte, short, ushort, int, uint, long和ulong)
Emumeration 这个概念早在C时代就有了,不过以前没怎么用过。
基本表达, 改变默认值和默认类型
Enumeration的默认值是从0开始的int,如下:
enum Direction
{
UP,
RIGHT
DOWN,
LEFT,
};
此时UP=0, DOWN=1...依此类推
改变默认值:
enum Direction
{
UP=1,
RIGHT=2,
DOWN=3,
LEFT=4,
};
改变类型(只能改变成:byte, sbyte, short, ushort, int, uint, long, ulong):
enum Direction : long
{
UP = 1111111111,
DOWN = 1111111112,
LEFT = 1111111113,
RIGHT = 1111111114
};
访问Enumeration变量的值
赋值前先cast(强制类型转换):
long direct = (long)Direction.UP;
Enumeration变量的文字描述
如果想要Enumeration返回一点有意义的string,从而用户能知道分别代表什么, 则按如下定义:
using System.ComponentModel; // 先添加该引用
enum Direction
{
[Description("this means facing to UP (Negtive Y)")]
UP = 1,
[Description("this means facing to RIGHT (Positive X)")]
RIGHT = 2,
[Description("this means facing to DOWN (Positive Y)")]
DOWN = 3,
[Description("this means facing to LEFT (Negtive X)")]
LEFT = 4
};
使用如下方法来获得文字描述:
using System.Reflection;
using System.ComponentModel;
public static String GetEnumDesc(Direction e)
{
FieldInfo EnumInfo = e.GetType().GetField(e.ToString());
DescriptionAttribute[] EnumAttributes = (DescriptionAttribute[]) EnumInfo.
GetCustomAttributes (typeof(DescriptionAttribute), false);
if (EnumAttributes.Length > 0)
{
return EnumAttributes[0].Description;
}
return e.ToString();
}
或者可以自己定义Discription Attributes
enum Direction
{
[EnumDescription("Rover is facing to UP (Negtive Y)")]
UP = 1,
[EnumDescription("Rover is facing to DOWN (Positive Y)")]
DOWN = 2,
[EnumDescription("Rover is facing to RIGHT (Positive X)")]
RIGHT = 3,
[EnumDescription("Rover is facing to LEFT (Negtive X)")]
LEFT = 4
};
AttributeUsage(AttributeTargets.Field)]
public class EnumDescriptionAttribute : Attribute
{
private string _text = "";
public string Text
{
get { return this._text; }
}
public EnumDescriptionAttribute(string text)
{
_text = text;
}
}
虽然现在,.net 中关于 enum 的 ToString 操作会输出这个 enum 的名字,不过,有很多情况下,我们希望使用不同的语言来显示它,或者,我们想要显示的字符串中有非法字符(比如空格,对于变量来讲,是非法字符,而对于显 示来说,就是一个普通的要求了),而这个属性,帮助我们显示 enum 所定义的字符串,不过,很可惜的,虽然任何的 enum 都是从 System.Enum 派生的,不过,我们没有办法改写它的 ToString 函数,所以,需要一个 Helper 类来帮助它的输出:
public class EnumStringHelper
{
public static string ToString(object o)
{
Type t = o.GetType();
string s = o.ToString();
EnumDescriptionAttribute[] os = (EnumDescriptionAttribute[])t.GetField(s).GetCustomAttributes(typeof(EnumDescriptionAttribute), false);
if (os != null && os.Length == 1)
{
return os[0].Text;
}
return s;
}
}
使用上,类似这样:
static void Main(string[] args)
{
Direction myDirection = Direction.DOWN;
string s = EnumStringHelper.ToString(myDirection);
Console.WriteLine("{0}", s);
Console.ReadKey();
}
转自<http://www.11zhuce.com/seo/751.html>(最后部分略有改动)
转载于:https://www.cnblogs.com/zhangchenliang/archive/2011/05/27/2059907.html
标签:facing,Direction,string,c#,enum,UP,用法,DOWN 来源: https://blog.csdn.net/weixin_33845477/article/details/93496112