1.msdn 在debug模式下的内存结构
（曾今在gaia引擎里看过类似的自己模仿实现的内存管理结构）
typedef struct _CrtMemBlockHeader
{
// Pointer to the block allocated just before this one:
struct _CrtMemBlockHeader *pBlockHeaderNext;
// Pointer to the block allocated just after this one:
struct _CrtMemBlockHeader *pBlockHeaderPrev;
char *szFileName; // File name
int nLine; // Line number
size_t nDataSize; // Size of user block
int nBlockUse; // Type of block
long lRequest; // Allocation number
// Buffer just before (lower than) the user's memory:
unsigned char gap[nNoMansLandSize];
} _CrtMemBlockHeader;
/* In an actual memory block in the debug heap,
* this structure is followed by:
* unsigned char data[nDataSize];
* unsigned char anotherGap[nNoMansLandSize];//防止内存写越界
*/
The “NoMansLand” buffers on either side of the user data area of the block are currently 4 bytes in size, and are filled with a known byte value used by the debug heap routines to verify that the limits of the user’s memory block have not been overwritten. The debug heap also fills new memory blocks with a known value. If you elect to keep freed blocks in the heap’s linked list as explained below, these freed blocks are also filled with a known value. Currently, the actual byte values used are as follows:
NoMansLand (0xFD)
The “NoMansLand” buffers on either side of the memory used by an application are currently filled with 0xFD.
Freed blocks (0xDD)
The freed blocks kept unused in the debug heap’s linked list when the _CRTDBG_DELAY_FREE_MEM_DF flag is set are currently filled with 0xDD.
New objects (0xCD)
New objects are filled with 0xCD when they are allocated.
2._CrtDumpMemLeaks()
msdn说明
The _CrtDumpMemoryLeaks function determines whether a memory leak has occurred since the start of program execution. When a leak is found, the debug header information for all of the objects in the heap is dumped in a user-readable form. When _DEBUG is not defined, calls to _CrtDumpMemoryLeaks are removed during preprocessing.
_CrtDumpMemoryLeaks is frequently called at the end of program execution to verify that all memory allocated by the application has been freed. The function can be called automatically at program termination by turning on the _CRTDBG_LEAK_CHECK_DF bit field of the _crtDbgFlag flag using the _CrtSetDbgFlag function.
_CrtDumpMemoryLeaks calls _CrtMemCheckpoint to obtain the current state of the heap and then scans the state for blocks that have not been freed. When an unfreed block is encountered, _CrtDumpMemoryLeaks calls _CrtMemDumpAllObjectsSince to dump information for all of the objects allocated in the heap from the start of program execution.
By default, internal C run-time blocks (_CRT_BLOCK ) are not included in memory dump operations. The _CrtSetDbgFlag function can be used to turn on the _CRTDBG_CHECK_CRT_DF bit of _crtDbgFlag to include these blocks in the leak detection process.
For more information about heap state functions and the _CrtMemState structure, see the Heap State Reporting Functions . For information about how memory blocks are allocated, initialized, and managed in the debug version of the base heap, see Memory Management and the Debug Heap .
应用：
#include "stdafx.h"
#include
#ifdef _DEBUG
#define DEBUG_CLIENTBLOCK new( _CLIENT_BLOCK, __FILE__, __LINE__)
#else
#define DEBUG_CLIENTBLOCK
#endif
#define _CRTDBG_MAP_ALLOC
#include
#ifdef _DEBUG
#define new DEBUG_CLIENTBLOCK
#endif //此部分用于使_CrtDum