vc中查memory leak

// to check memory leak
#define  _CRTDBG_MAP_ALLOC
#include <stdlib.h>
#include <crtdbg.h>

//...

// will print LEAKS information to Output window
_CrtDumpMemoryLeaks();

// or
// if app has multi-exit point, can use following function at the beginning of program to set the check on, it will excute when the app eixt
_CrtSetDbgFlag ( _CRTDBG_ALLOC_MEM_DF | _CRTDBG_LEAK_CHECK_DF );