This function frees a memory block allocated from a heap by the HeapAlloc or HeapReAlloc function.
At a Glance
| Header file: | Winbase.h |
| Windows CE versions: | 1.0 and later |
Syntax
BOOL HeapFree(HANDLE hHeap, DWORD dwFlags, LPVOID lpMem);
Parameters
hHeap
[in] Handle to the heap whose memory block the function frees. This parameter is a handle returned by the HeapCreate or GetProcessHeap function.
dwFlags
[in] Specifies several controllable aspects of freeing a memory block. Only one flag is currently defined; however, all other flag values are reserved for future use. Specifying this flag will override the corresponding flag specified in the flOptions parameter when the heap was created by using the HeapCreate function:
| Value | Description |
| HEAP_NO_SERIALIZE | Specifies that mutual exclusion will not be used while HeapFree is accessing the heap. |
| This flag should not be specified when accessing the process heap. The system may create additional threads within the application’s process that simultaneously access the process heap. |
lpMem
[in] Pointer to the memory block to free. This pointer is returned by the HeapAlloc or HeapReAlloc function.
Return Values
Nonzero indicates success. Zero indicates failure. To get extended error information, call GetLastError.
Remarks
Serialization ensures mutual exclusion when two or more threads attempt to simultaneously allocate or free blocks from the same heap. There is a small performance cost to serialization, but it must be used whenever multiple threads allocate and free memory from the same heap. Setting the HEAP_NO_SERIALIZE flag eliminates mutual exclusion on the heap. Without serialization, two or more threads that use the same heap handle might attempt to allocate or free memory simultaneously, likely causing corruption in the heap. The HEAP_NO_SERIALIZE flag can, therefore, be safely used only in the following situations:
See Also