Marshal.ReAllocCoTaskMem Method

Resizes a block of memory previously allocated with AllocCoTaskMem.

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

public static IntPtr ReAllocCoTaskMem (
	IntPtr pv,
	int cb
public static IntPtr ReAllocCoTaskMem (
	IntPtr pv, 
	int cb
public static function ReAllocCoTaskMem (
	pv : IntPtr, 
	cb : int
) : IntPtr



A pointer to memory allocated with AllocCoTaskMem.


The new size of the allocated block.

Return Value

An integer representing the address of the block of memory reallocated. This memory must be released with FreeCoTaskMem.

Exception typeCondition


There is insufficient memory to satisfy the request.

ReAllocCoTaskMem is one of two memory reallocation API methods in the Marshal class. (ReAllocHGlobal is the other.) The beginning of the reallocated memory content is the same as the original content; however, the entire memory block can be in a different location. This method exposes the CoTaskMemRealloc COM API method, which is referred to as the COM task memory allocator. For additional information about CoTaskMemRealloc, see the MSDN Library.


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 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, 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.

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0