IMalloc:IUnknown

Article
06/30/2006

This interface allocates, frees, and manages memory.

When to Implement

In general, you should not implement IMalloc, instead use the COM implementation, which is guaranteed to be thread-safe in managing task memory. You get a pointer to the COM task allocator object's IMalloc through a call to the CoGetMalloc function.

When to Use

Call the methods of IMalloc to allocate and manage memory. The COM libraries and object handlers also call the IMalloc methods to manage memory. Object handlers should call CoGetMalloc to get a pointer to the IMalloc implementation on the task allocator object and use the implementation of those methods to manage task memory.

The IMalloc methods Alloc, Free, and Realloc are similar to the C library functions malloc, free, and realloc. For debugging, refer to the functions CoRegisterMallocSpy and CoRevokeMallocSpy.

Methods

The following table shows the methods for this interface in the order that the compiler calls the methods. Like all COM interfaces, this interface inherits the methods for the IUnknown interface.

IUnknown method	Description
QueryInterface	Returns pointers to supported interfaces.
AddRef	Increments reference count.
Release	Decrements reference count.

IMalloc method	Description
Alloc	Allocates a block of memory.
Realloc	Changes the size of a previously allocated block of memory.
Free	Frees a previously allocated block of memory.
GetSize	Returns the size in bytes of a previously allocated block of memory.
DidAlloc	Determines whether this instance of IMalloc was used to allocate the specified block of memory.
HeapMinimize	Minimizes the heap by releasing unused memory to the operating system.

Remarks

To determine whether the platform supports this interface, see Determining Supported COM APIs.

Requirements

OS Versions: Windows CE 3.0 and later.
Header: Objidl.h, Objidl.idl.
Link Library: Ole32.lib