FieldOffsetAttribute Class
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FieldOffsetAttribute Class


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

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


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


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


When implemented in a derived class, gets a unique identifier for this Attribute.(Inherited from Attribute.)


Gets the offset from the beginning of the structure to the beginning of the field.


This API supports the product infrastructure and is not intended to be used directly from your code. Returns a value that indicates whether this instance is equal to a specified object.(Inherited from Attribute.)


Returns the hash code for this instance.(Inherited from Attribute.)


Gets the Type of the current instance.(Inherited from Object.)


When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class.(Inherited from Attribute.)


When overridden in a derived class, returns a value that indicates whether this instance equals a specified object.(Inherited from Attribute.)


Returns a string that represents the current object.(Inherited from Object.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.GetIDsOfNames(Guid, IntPtr, UInt32, UInt32, IntPtr)

Maps a set of names to a corresponding set of dispatch identifiers.(Inherited from Attribute.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.GetTypeInfo(UInt32, UInt32, IntPtr)

Retrieves the type information for an object, which can be used to get the type information for an interface.(Inherited from Attribute.)


Retrieves the number of type information interfaces that an object provides (either 0 or 1).(Inherited from Attribute.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr)

Provides access to properties and methods exposed by an object.(Inherited from Attribute.)

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.

Legacy Code Example

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

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.

Universal Windows Platform
Available since 4.5
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1

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

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