`_recalloc_dbg`

Article
02/07/2023

Reallocates an array and initializes its elements to 0 (debug version only).

Syntax

void *_recalloc_dbg(
   void *userData,
   size_t num,
   size_t size,
   int blockType,
   const char *filename,
   int linenumber
);

Parameters

userData
Pointer to the previously allocated memory block.

number
Requested number of memory blocks.

size
Requested size of each memory block (bytes).

blockType
Requested type of memory block: _CLIENT_BLOCK or _NORMAL_BLOCK.

For information about the allocation block types and how they're used, see Types of blocks on the debug heap.

filename
Pointer to name of the source file that requested allocation operation or NULL.

linenumber
Line number in the source file where allocation operation was requested or NULL.

The filename and linenumber parameters are only available when _recalloc_dbg has been called explicitly or the _CRTDBG_MAP_ALLOC preprocessor constant has been defined.

Return value

On successful completion, this function either returns a pointer to the user portion of the reallocated memory block, calls the new handler function, or returns NULL. For a complete description of the return behavior, see the following Remarks section. For more information about how the new handler function is used, see the _recalloc function.

Remarks

_recalloc_dbg is a debug version of the _recalloc function. When _DEBUG isn't defined, each call to _recalloc_dbg is reduced to a call to _recalloc. Both _recalloc and _recalloc_dbg reallocate a memory block in the base heap, but _recalloc_dbg accommodates several debugging features: buffers on either side of the user portion of the block to test for leaks, a block type parameter to track specific allocation types, and filename/linenumber information to determine the origin of allocation requests.

_recalloc_dbg reallocates the specified memory block with slightly more space than the requested size (number * size) which might be greater or less than the size of the originally allocated memory block. The extra space is used by the debug heap manager to link the debug memory blocks and to provide the application with debug header information and overwrite buffers. The reallocation might result in both moving the original memory block to a different location in the heap, and changing the size of the memory block. The user portion of the block is filled with the value 0xCD and each of the overwrite buffers are filled with 0xFD.

_recalloc_dbg sets errno to ENOMEM if a memory allocation fails; EINVAL is returned if the amount of memory needed (including the overhead mentioned previously) exceeds _HEAP_MAXREQ. For information about this and other error codes, see errno, _doserrno, _sys_errlist, and _sys_nerr.

For information about how memory blocks are allocated, initialized, and managed in the debug version of the base heap, see CRT debug heap details. For information about the differences between standard heap functions and debug versions, see Debug versions of heap allocation functions.

Requirements

Routine	Required header
`_recalloc_dbg`	<crtdbg.h>

For more compatibility information, see Compatibility.

Libraries

Debug versions of C run-time libraries only.

Share via