This documentation is archived and is not being maintained.

Marshal.DestroyStructure Method

Frees all substructures pointed to by the specified unmanaged memory block.

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

public static void DestroyStructure (
	IntPtr ptr,
	Type structuretype
/** @attribute ComVisibleAttribute(true) */ 
public static void DestroyStructure (
	IntPtr ptr, 
	Type structuretype
public static function DestroyStructure (
	ptr : IntPtr, 
	structuretype : Type
Not applicable.



A pointer to an unmanaged block of memory.


Type of a formatted class. This provides the layout information necessary to delete the buffer in the ptr parameter.

Exception typeCondition


structureType has an automatic layout. Use sequential or explicit instead.

You can use this method to free reference-type fields, such as strings, of an unmanaged structure. Unlike its fields, a structure can be a value type or reference type. Value-type structures containing value-type fields (all blittable) have no references whose memory must be freed. StructureToPtr uses this method to prevent memory leaks when reusing memory occupied by a structure.

DestroyStructure calls the SysFreeString COM API method, which in turn frees an allocated string. For additional information about SysFreeString, see the MSDN Library.

In addition to DestroyStructure, the Marshal class provides two other memory-deallocation methods: Marshal.FreeCoTaskMem and Marshal.FreeHGlobal.


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.

Windows 98, Windows Server 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 Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0