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FieldOffsetAttribute Class

.NET Framework 4.5

Other Versions

Indicates the physical position of fields within the unmanaged representation of a class or structure.

Inheritance Hierarchy

System.Object
System.Attribute
System.Runtime.InteropServices.FieldOffsetAttribute

Namespace: System.Runtime.InteropServices
Assembly: mscorlib (in mscorlib.dll)

Syntax

C++

[ComVisibleAttribute(true)]
[AttributeUsageAttribute(AttributeTargets.Field, Inherited = false)]
public sealed class FieldOffsetAttribute : Attribute

The FieldOffsetAttribute type exposes the following members.

Constructors

	Name	Description
	FieldOffsetAttribute	Initializes a new instance of the FieldOffsetAttribute class with the offset in the structure to the beginning of the field.

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Properties

	Name	Description
	TypeId	When implemented in a derived class, gets a unique identifier for this Attribute. (Inherited from Attribute.)
	Value	Gets the offset from the beginning of the structure to the beginning of the field.

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Methods

	Name	Description
	Equals	Infrastructure. Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute.)
	GetHashCode	Returns the hash code for this instance. (Inherited from Attribute.)
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	IsDefaultAttribute	When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class. (Inherited from Attribute.)
	Match	When overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute.)
	ToString	Returns a string that represents the current object. (Inherited from Object.)

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Explicit Interface Implementations

	Name	Description
	_Attribute.GetIDsOfNames	Maps a set of names to a corresponding set of dispatch identifiers. (Inherited from Attribute.)
	_Attribute.GetTypeInfo	Retrieves the type information for an object, which can be used to get the type information for an interface. (Inherited from Attribute.)
	_Attribute.GetTypeInfoCount	Retrieves the number of type information interfaces that an object provides (either 0 or 1). (Inherited from Attribute.)
	_Attribute.Invoke	Provides access to properties and methods exposed by an object. (Inherited from Attribute.)

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Remarks

You can apply this attribute to fields.

This attribute is used when System.Runtime.InteropServices.StructLayoutAttribute, with LayoutKind.Explicit passed to its constructor, is applied to a class or structure to specify the offset of each non- static or constant member within the unmanaged representation of that class or structure.

Examples

The following example demonstrates how to apply the FieldOffsetAttribute to members of a class with an explicit layout.

C++

[StructLayout(LayoutKind.Explicit)]
public class SYSTEM_INFO
{
[FieldOffset(0)] public ulong OemId;
[FieldOffset(8)] public ulong PageSize;
[FieldOffset(16)] public ulong ActiveProcessorMask;
[FieldOffset(24)] public ulong NumberOfProcessors;
[FieldOffset(32)] public ulong ProcessorType;
}

For a larger example, see the System.Runtime.InteropServices.StructLayoutAttribute class.

Version Information

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

Platforms

Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Reference

System.Runtime.InteropServices Namespace

LayoutKind

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