_crtDbgFlag
The _crtDbgFlag flag consists of five bit-fields that control how memory allocations on the debug version of the heap are tracked, verified, reported, and dumped. The bit fields of the flag are set using the _CrtSetDbgFlag function. This flag and its bit fields are declared in Crtdbg.h. This flag is only available when the _DEBUG flag has been defined in the application.
For more information about using this flag along with other debug functions, see Heap state reporting functions.