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Marshal.AllocCoTaskMem Method

Allocates a block of memory of specified size from the COM task memory allocator.

[Visual Basic]
Public Shared Function AllocCoTaskMem( _
   ByVal cb As Integer _
) As IntPtr
public static IntPtr AllocCoTaskMem(
 int cb
public: static IntPtr AllocCoTaskMem(
 int cb
public static function AllocCoTaskMem(
   cb : int
) : IntPtr;


The size of the block of memory to be allocated.

Return Value

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


Exception Type Condition
OutOfMemoryException There is insufficient memory to satisfy the request.


AllocCoTaskMem is one of two memory allocation API methods in the Marshal class. (Marshal.AllocHGlobal is the other.) The initial memory content returned is undefined, and the allocated memory can be larger than the requested number of bytes. This method exposes the CoTaskMemAlloc COM API method, which is referred to as the COM task memory allocator. For additional information about CoTaskMemAlloc, see the MSDN Library.

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.


Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

.NET Framework Security: 

See Also

Marshal Class | Marshal Members | System.Runtime.InteropServices Namespace | AllocHGlobal | FreeCoTaskMem