MFC程序中检查内存泄漏的手段

 

CMemoryState

CMemoryState does not have a base class.

CMemoryState provides a convenient way to detect memory leaks in your program. A “memory leak” occurs when memory for an object is allocated on the heap but not deallocated when it is no longer required. Such memory leaks can eventually lead to out-of-memory errors. There are several ways to allocate and deallocate memory in your program:

• Using the malloc/free family of functions from the run-time library.
  
  
• Using the Windows API memory management functions, LocalAlloc/LocalFree and GlobalAlloc/GlobalFree.
  
  
• Using the C++ new and delete operators.

The CMemoryState diagnostics only help detect memory leaks caused when memory allocated using the new operator is not deallocated using delete. The other two groups of memory-management functions are for non-C++ programs, and mixing them with new and delete in the same program is not recommended. An additional macro, DEBUG_NEW, is provided to replace the new operator when you need file and line-number tracking of memory allocations. DEBUG_NEW is used whenever you would normally use the new operator.

As with other diagnostics, the CMemoryState diagnostics are only available in debug versions of your program. A debug version must have the _DEBUG constant defined.

If you suspect your program has a memory leak, you can use the Checkpoint, Difference, and DumpStatistics functions to discover the difference between the memory state (objects allocated) at two different points in program execution. This information can be useful in determining whether a function is cleaning up all the objects it allocates.

If simply knowing where the imbalance in allocation and deallocation occurs does not provide enough information, you can use the DumpAllObjectsSince function to dump all objects allocated since the previous call to Checkpoint. This dump shows the order of allocation, the source file and line where the object was allocated (if you are using DEBUG_NEW for allocation), and the derivation of the object, its address, and its size. DumpAllObjectsSince also calls each object’s Dump function to provide information about its current state.

在你怀疑有问题的代码前申明一个CMemoryState对象，调用其Checkpoint()函数，在你
认为有问题代码结束后再申明一个CMemoryState对象，再调用Checkpoint()函数，申明
第3个CMemoryState对象，调用其Difference()函数，就可以检查有无内存泄漏，若有
调用DumpStatistics()函数输出统计结果。