LocalReAlloc

The LocalReAlloc function changes the size or the attributes of a specified local memory object. The size can increase or decrease.

HLOCAL LocalReAlloc(

HLOCAL hMem,	// handle of local memory object
UINT uBytes,	// new size of block
UINT uFlags	// how to reallocate object
);

Parameters

hMem

Identifies the local memory object to be reallocated. This handle is returned by either the LocalAlloc or LocalReAlloc function.

uBytes

Specifies the new size, in bytes, of the memory block. If this parameter is zero and the uFlags parameter specifies the LMEM_MOVEABLE flag, the function returns a handle to a memory object that is marked as discarded. If uFlags specifies the LMEM_MODIFY flag, this parameter is ignored.

uFlags

Specifies how to reallocate the local memory object. If the LMEM_MODIFY flag is specified, this parameter modifies the attributes of the memory object, and the uBytes parameter is ignored. Otherwise, this parameter controls the reallocation of the memory object.

The LMEM_MODIFY flag can be combined with either or both of the following flags:

Flag

Meaning

LMEM_DISCARDABLE

Allocates discardable memory if the LMEM_MODIFY flag is also specified. This flag is ignored, unless the object was previously allocated as movable or the LMEM_MOVEABLE flag is also specified.

LMEM_MOVEABLE

You cannot combine LMEM_MOVEABLE with LMEM_MODIFY to change a fixed memory object into a movable one. The function returns an error if an application attempts this.

If uFlags does not specify LMEM_MODIFY, this parameter can be any combination of the following flags:

Flag

Meaning

LMEM_MOVEABLE

If uBytes is zero, discards a previously movable and discardable memory block. If the object's lock count is not zero or the block is not movable and discardable, the function fails.

If uBytes is nonzero, enables the system to move the reallocated block to a new location without changing the movable or fixed attribute of the memory object. If the object is fixed, the handle returned may be different from the handle specified in the hMem parameter. If the object is movable, the block can be moved without invalidating the handle, even if the object is currently locked by a previous call to the LocalLock function. To get the new address of the memory block, use LocalLock.

LMEM_NOCOMPACT

Prevents memory from being compacted or discarded to satisfy the allocation request.

LMEM_ZEROINIT

Causes the additional memory contents to be initialized to zero if the memory object is growing in size.

Return Values

If the function succeeds, the return value is the handle of the reallocated memory object.

If the function fails, the return value is NULL. To get extended error information, call GetLastError.

Remarks

If LocalReAlloc reallocates a movable object, the return value is the handle of the memory object. To convert the handle to a pointer, use the LocalLock function.

If LocalReAlloc reallocates a fixed object, the value of the handle returned is the address of the first byte of the memory block. To access the memory, a process can simply cast the return value to a pointer.

See Also

LocalAlloc, LocalFree, LocalLock

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