---
description: "Learn more about: _aligned_offset_malloc"
title: "_aligned_offset_malloc"
ms.date: "4/2/2020"
api_name: ["_aligned_offset_malloc", "_o__aligned_offset_malloc"]
api_location: ["msvcrt.dll", "msvcr80.dll", "msvcr90.dll", "msvcr100.dll", "msvcr100_clr0400.dll", "msvcr110.dll", "msvcr110_clr0400.dll", "msvcr120.dll", "msvcr120_clr0400.dll", "ucrtbase.dll", "api-ms-win-crt-heap-l1-1-0.dll"]
api_type: ["DLLExport"]
topic_type: ["apiref"]
f1_keywords: ["_aligned_offset_malloc", "aligned_offset_malloc"]
helpviewer_keywords: ["_aligned_offset_malloc function", "aligned_offset_malloc function"]
ms.assetid: 447681a3-7c95-4655-86ba-fa3a4ca4c521
---
# `_aligned_offset_malloc`

Allocates memory on a specified alignment boundary.

## Syntax

```C
void * _aligned_offset_malloc(
   size_t size,
   size_t alignment,
   size_t offset
);
```

### Parameters

*`size`*\
The size of the requested memory allocation.

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

*`offset`*\
The offset into the memory allocation to force the alignment.

## Return value

A pointer to the memory block that was allocated or `NULL` if the operation failed.

## Remarks

**`_aligned_offset_malloc`** is useful in situations where alignment is needed on a nested element; for example, if alignment was needed on a nested class.

**`_aligned_offset_malloc`** is based on `malloc`; for more information, see [`malloc`](malloc.md).

**`_aligned_offset_malloc`** is marked `__declspec(noalias)` and `__declspec(restrict)`, meaning that the function is guaranteed not to modify global variables and that the pointer returned isn't aliased. For more information, see [`noalias`](../../cpp/noalias.md) and [`restrict`](../../cpp/restrict.md).

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`](../errno-doserrno-sys-errlist-and-sys-nerr.md). Also, **`_aligned_offset_malloc`** validates its parameters. If *`alignment`* isn't a power of 2, or if *`offset`* is non-zero and greater than or equal to *`size`*, this function invokes the invalid parameter handler, as described in [Parameter validation](../parameter-validation.md). If execution is allowed to continue, this function returns `NULL` and sets `errno` to `EINVAL`.

By default, this function's global state is scoped to the application. To change this behavior, see [Global state in the CRT](../global-state.md).

## Requirements

| Routine | Required header |
|---|---|
| **`_aligned_offset_malloc`** | \<malloc.h> |

## Example

For more information, see [`_aligned_malloc`](aligned-malloc.md).

## See also

[Data alignment](../data-alignment.md)