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Marshal.OffsetOf Method

.NET Framework 2.0

Other Versions

Returns the field offset of the unmanaged form of the managed class.

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

Syntax

C++

Copy

public static IntPtr OffsetOf (
	Type t,
	string fieldName
)

Copy

public static IntPtr OffsetOf (
	Type t, 
	String fieldName
)

JScript

Copy

public static function OffsetOf (
	t : Type, 
	fieldName : String
) : IntPtr

Parameters

t: A Type, specifying the specified class. You must apply the StructLayoutAttribute to the class.

fieldName: The field within the t parameter.

Return Value

The offset, in bytes, for the fieldName parameter within the platform invoke declared class t.

Exceptions

Exception type	Condition
ArgumentException	The class cannot be exported as a structure or the field is nonpublic. Beginning with the .NET Framework version 2.0, the field may be private.
ArgumentNullException	The t parameter is a null reference (Nothing in Visual Basic).

Remarks

OffsetOf provides the offset in terms of the unmanaged structure layout, which does not necessarily correspond to the offset of the managed structure layout. Marshaling the structure can transform the layout and alter the offset. The t parameter can be a value type or a formatted reference type (with either a sequential or explicit layout). You can obtain the size of the entire layout by using the Marshal.SizeOf method. For additional information, see Default Marshaling for Value Types.

Note
Beginning with the .NET Framework version 2.0, OffsetOf may expose private fields.

Note
This method uses SecurityAction.LinkDemand to prevent it from being called from untrusted code; only the immediate caller is required to have SecurityPermissionAttribute.UnmanagedCode permission. If your code can be called from partially trusted code, do not pass user input to Marshal class methods without validation. For important limitations on using the LinkDemand member, see Demand vs. LinkDemand.

Note

This method uses SecurityAction.LinkDemand to prevent it from being called from untrusted code; only the immediate caller is required to have SecurityPermissionAttribute.UnmanagedCode permission. If your code can be called from partially trusted code, do not pass user input to Marshal class methods without validation. For important limitations on using the LinkDemand member, see Demand vs. LinkDemand.

.NET Framework Security

SecurityPermission for permission to call unmanaged code. Associated enumeration: UnmanagedCode Security action: LinkDemand

Platforms

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

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

Version Information

.NET Framework

Supported in: 2.0, 1.1, 1.0

Reference

Marshal Class
Marshal Members
System.Runtime.InteropServices Namespace
SizeOf

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