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---
# _heapadd
Adds memory to the heap.  
  
> [!IMPORTANT]
>  This function is obsolete. Beginning in Visual Studio 2015, it is not available in the CRT.  
  
## Syntax  
  
```  
int _heapadd(   
   void *memblock,  
   size_t size   
);  
```  
  
#### Parameters  
 `memblock`  
 Pointer to the heap memory.  
  
 `size`  
 Size of memory to add, in bytes.  
  
## Return Value  
 If successful, `_heapadd` returns 0; otherwise, the function returns -1 and sets `errno` to `ENOSYS`.  
  
 For more information about this and other return codes, see [_doserrno, errno, _sys_errlist, and _sys_nerr](../c-runtime-library/errno-doserrno-sys-errlist-and-sys-nerr.md).  
  
## Remarks  
 Beginning with Visual C++ version 4.0, the underlying heap structure was moved to the C run-time libraries to support the new debugging features. As a result, `_heapadd` is no longer supported on any platform that is based on the Win32 API.  
  
## Requirements  
  
|Routine|Required header|Optional header|  
|-------------|---------------------|---------------------|  
|`_heapadd`|\<malloc.h>|\<errno.h>|  
  
 For more compatibility information, see [Compatibility](../c-runtime-library/compatibility.md) in the Introduction.  
  
## See Also  
 [Memory Allocation](../c-runtime-library/memory-allocation.md)   
 [free](../c-runtime-library/reference/free.md)   
 [_heapchk](../c-runtime-library/reference/heapchk.md)   
 [_heapmin](../c-runtime-library/reference/heapmin.md)   
 [_heapset](../c-runtime-library/heapset.md)   
 [_heapwalk](../c-runtime-library/reference/heapwalk.md)   
 [malloc](../c-runtime-library/reference/malloc.md)   
 [realloc](../c-runtime-library/reference/realloc.md)