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<Type Name="FlagsAttribute" FullName="System.FlagsAttribute" FullNameSP="System_FlagsAttribute" Maintainer="ecma">
<TypeSignature Language="ILASM" Value=".class public serializable FlagsAttribute extends System.Attribute" />
<TypeSignature Language="C#" Value="public class FlagsAttribute : Attribute" />
<MemberOfLibrary>BCL</MemberOfLibrary>
<AssemblyInfo>
<AssemblyName>mscorlib</AssemblyName>
<AssemblyPublicKey>[00 00 00 00 00 00 00 00 04 00 00 00 00 00 00 00 ]</AssemblyPublicKey>
<AssemblyVersion>1.0.5000.0</AssemblyVersion>
<AssemblyVersion>2.0.0.0</AssemblyVersion>
</AssemblyInfo>
<ThreadingSafetyStatement>All public static members of this type are safe for multithreaded operations. No instance members are guaranteed to be thread safe.</ThreadingSafetyStatement>
<Base>
<BaseTypeName>System.Attribute</BaseTypeName>
</Base>
<Interfaces />
<Attributes>
<Attribute>
<AttributeName>System.Runtime.InteropServices.ComVisible(true)</AttributeName>
</Attribute>
<Attribute>
<AttributeName>System.AttributeUsage(System.AttributeTargets.Enum, Inherited=false)</AttributeName>
</Attribute>
</Attributes>
<Docs>
<summary>
<para> Indicates that the <see cref="T:System.Enum" /> targeted by the current attribute is declared as a bit-field.</para>
</summary>
<remarks>
<para> The <see cref="T:System.FlagsAttribute" /> class provides the consumer of a <see cref="T:System.Enum" /> the information that the
enumeration is to be used as a bit-field. Additionally, when formatting a <see cref="T:System.Enum" />, using the <see cref="T:System.FlagsAttribute" /> causes a value that is a bitwise OR combination of
multiple fields to print correctly.</para>
<block subset="none" type="note">
<para> Bit-fields are generally used for lists of
elements that might occur in combination; whereas enumeration constants are
generally used for lists of mutually exclusive elements. Therefore, bit-fields
are designed to be combined with the bitwise OR operator to generate unnamed
values, whereas enumerated constants are not. Languages
vary in their usage of bit-fields compared to enumeration constants.</para>
<para>This attribute can only be applied to enumerations.</para>
</block>
</remarks>
<example>
<para> The following example demonstrates the use of
<see cref="T:System.FlagsAttribute" /> on the formatting of a
<see cref="T:System.Enum" />. With this attribute, the <paramref name="Position" /> enumeration is used as a bit-field, and the value 3 (Top
| Left) is considered a valid value for the enumeration when formatting. Without this
attribute, the enumeration <paramref name="Color" /> is not used as a
bit-field, and the value 3 (Red | Blue) is not considered a valid value for the
enumeration when formatting.</para>
<code lang="C#">
using System;
[FlagsAttribute()]
public enum Position {
Top = 0x1,
Left = 0x2,
Bottom = 0x4,
Right = 0x8
}
//enum Color declared without FlagsAttribute
public enum Color {
Red = 0x1,
Blue = 0x2,
Yellow = 0x4
}
public class enumFormat {
public static void Main() {
Position p = Position.Top | Position.Left;
Console.WriteLine("Position: {0}", p);
Color c = Color.Red | Color.Blue;
Console.WriteLine("Color: {0}", c);
}
}
</code>
<para>The output is</para>
<c>
<para>Position: Top, Left</para>
<para>Color: 3</para>
</c>
</example>
</Docs>
<Members>
<Member MemberName=".ctor">
<MemberSignature Language="ILASM" Value="public rtspecialname specialname instance void .ctor()" />
<MemberSignature Language="C#" Value="public FlagsAttribute ();" />
<MemberType>Constructor</MemberType>
<ReturnValue />
<Parameters />
<Docs>
<summary>
<para> Constructs a new instance of the <see cref="T:System.FlagsAttribute" /> class.
</para>
</summary>
<remarks>To be added.</remarks>
</Docs>
<Excluded>0</Excluded>
<AssemblyInfo>
<AssemblyVersion>1.0.5000.0</AssemblyVersion>
<AssemblyVersion>2.0.0.0</AssemblyVersion>
</AssemblyInfo>
</Member>
</Members>
<TypeExcluded>0</TypeExcluded>
</Type>
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