1、关于enum的定义
enum Fabric
{
Cotton = 1,
Silk = 2,
Wool = 4,
Rayon = 8,
Other = 128
}
2、符号名和常数值的互相转换
Fabric fab = Fabric.Cotton;
int fabNum = (int)fab;//转换为常数值。必须使用强制转换。
Fabric fabString = (Fabric)1;//常数值转换成符号名。如果使用ToString(),则是((Fabric)1).ToString(),注意必须有括号。
string fabType = fab.ToString();//显示符号名
string fabVal = fab.ToString ("D");//显示常数值
3、获得所有符号名的方法(具体参见Enum类)
public enum MyFamily
{
YANGZHIPING = 1,
GUANGUIQIN = 2,
YANGHAORAN = 4,
LIWEI = 8,
GUANGUIZHI = 16,
LISIWEN = 32,
LISIHUA = 64,
}
foreach (string s in Enum.GetNames(typeof(MyFamily)))
{
Console.WriteLine(s);
}
4、将枚举作为位标志来处理
根据下面的两个例子,粗略地说,一方面,设置标志[Flags]或者[FlagsAttribute],则表明要将符号名列举出来;另一方面,可以通过强制转换,将数字转换为符号名。说不准确。看下面的例子体会吧。注意:
- 例一:
Fabric fab = Fabric.Cotton | Fabric.Rayon | Fabric.Silk;
Console.WriteLine("MyFabric = {0}", fab);//输出:Fabric.Cotton | Fabric.Rayon | Fabric.Silk;
- 例二:
class FlagsAttributeDemo
{
// Define an Enum without FlagsAttribute.
enum SingleHue : short
{
Black = 0,
Red = 1,
Green = 2,
Blue = 4
};
// Define an Enum with FlagsAttribute.
[FlagsAttribute]
enum MultiHue : short
{
Black = 0,
Red = 1,
Green = 2,
Blue = 4
};
static void Main( )
{
Console.WriteLine(
"This example of the FlagsAttribute attribute n" +
"generates the following output." );
Console.WriteLine(
"nAll possible combinations of values of an n" +
"Enum without FlagsAttribute:n" );
// Display all possible combinations of values.
for( int val = 0; val <= 8; val++ )
Console.WriteLine( "{0,3} – {1}", val, ( (SingleHue)val ).ToString( ) );
Console.WriteLine( "nAll possible combinations of values of an n" + "Enum with FlagsAttribute:n" );
// Display all possible combinations of values.
// Also display an invalid value.
for( int val = 0; val <= 8; val++ )
Console.WriteLine ( "{0,3} – {1}", val, ( (MultiHue)val ).ToString( ) );
}
}
/*
This example of the FlagsAttribute attribute
generates the following output.
All possible combinations of values of an
Enum without FlagsAttribute:
0 – Black
1 – Red
2 – Green
3 – 3
4 – Blue
5 – 5
6 – 6
7 – 7
8 – 8
All possible combinations of values of an
Enum with FlagsAttribute:
0 – Black
1 – Red
2 – Green
3 – Red, Green
4 – Blue
5 – Red, Blue
6 – Green, Blue
7 – Red, Green, Blue
8 – 8
*/
5、枚举作为函数参数。经常和switch结合起来使用。下面举例
public static double GetPrice(Fabric fab)
{
switch (fab)
{
case Fabric.Cotton:
return (3.55);
case Fabric.Silk:
return (5.65);
case Fabric.Wool:
return (4.05);
case Fabric.Rayon:
return (3.20);
case Fabric.Other:
return (2.50);
default:
return (0.0);
}
}
6、上面三点一个完整的例子
//enum的定义
public enum Fabric : short
{
Cotton = 1,
Silk = 2,
Wool = 3,
Rayon = 8,
Other = 128
}
//将枚举作为参数传递
public static double GetPrice(Fabric fab)
{
switch (fab)
{
case Fabric.Cotton: return (3.55);
case Fabric.Silk : return (5.65);
case Fabric.Wool: return (4.05);
case Fabric.Rayon: return (3.20);
case Fabric.Other: return (2.50);
default: return (0.0);
}
}
public static void Main()
{
Fabric fab = Fabric.Cotton;
int fabNum = (int)fab;
string fabType = fab.ToString();
string fabVal = fab.ToString ("D");
double cost = GetPrice(fab);
Console.WriteLine("fabNum = {0}nfabType = {1}nfabVal = {2}n", fabNum, fabType, fabVal);
Console.WriteLine("cost = {0}", cost);
}
7、Enum类的使用
Enum.IsDefinde
、Enum.Parse
两种方法经常一起使用,来确定一个值或符号是否是一个枚举的成员,然后创建一个实例。Enum.GetName
打印出一个成员的值;Enum.GetNames
打印出所有成员的值。其中注意**“`typeof“`**的使用。这一点很重要。
public enum MyFamily
{
YANGZHIPING = 1,
GUANGUIQIN = 2,
YANGHAORAN = 4,
LIWEI = 8,
GUANGUIZHI = 16,
LISIWEN = 32,
LISIHUA = 64,
}
string s = "YANGHAORAN";
if (Enum.IsDefined(typeof(MyFamily), s))
{
MyFamily f = (MyFamily)Enum.Parse(typeof(MyFamily), s);
GetMyFamily(f);
Console.WriteLine("The name is:" + Enum. GetName(typeof(MyFamily), 2));
string[] sa = Enum.GetNames(typeof(MyFamily));
foreach (string ss in sa)
{
Console.WriteLine(ss);
}
}