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The latest version of this topic can be found at _aligned_offset_realloc.

Changes the size of a memory block that was allocated with _aligned_malloc or _aligned_offset_malloc.

void * _aligned_offset_realloc(  
   void *memblock,   
   size_t size,   
   size_t alignment,  
   size_t offset  


The current memory block pointer.

The size of the memory allocation.

The alignment value, which must be an integer power of 2.

The offset into the memory allocation to force the alignment.

_aligned_offset_realloc returns a void pointer to the reallocated (and possibly moved) memory block. The return value is NULL if the size is zero and the buffer argument is not NULL, or if there is not enough available memory to expand the block to the given size. In the first case, the original block is freed. In the second case, the original block is unchanged. The return value points to a storage space that is guaranteed to be suitably aligned for storage of any type of object. To get a pointer to a type other than void, use a type cast on the return value.

_aligned_offset_realloc is marked __declspec(noalias) and __declspec(restrict), meaning that the function is guaranteed not to modify global variables and that the pointer returned is not aliased. For more information, see noalias and restrict.

Like _aligned_offset_malloc, _aligned_offset_realloc allows a structure to be aligned at an offset within the structure.

_aligned_offset_realloc is based on malloc. For more information about using _aligned_offset_malloc, see malloc. If memblock is NULL, the function calls _aligned_offset_malloc internally.

This function sets errno to ENOMEM if the memory allocation failed or if the requested size was greater than _HEAP_MAXREQ. For more information about errno, see errno, _doserrno, _sys_errlist, and _sys_nerr. Also, _aligned_offset_realloc validates its parameters. If alignment is not a power of 2 or if offset is greater than or equal to size and nonzero, this function invokes the invalid parameter handler, as described in Parameter Validation. If execution is allowed to continue, this function returns NULL and sets errno to EINVAL.

RoutineRequired header

For more information, see _aligned_malloc.

Data Alignment