CRT memory leak detect sample

#include "stdafx.h"
#include <windows.h>
#define _CRTDBG_MAP_ALLOC
#include "crtdbg.h"
#define _DEBUG

#ifdef _DEBUG
#define new DEBUG_NEW
#endif

#ifdef _DEBUG
#ifndef DEBUG_NEW
#define DEBUG_NEW   new( _NORMAL_BLOCK, __FILE__, __LINE__)
#endif
#endif

class X
   {
   public:
      X::X() : m_value(123) {}
   private:
      int m_value;
   };

void test()
{
X *p1 = 0;
X *p2 = 0;
X *p3 = 0;

p1 = new X();
p2 = new X();
p3 = new X();
delete p1;
delete p3;

}

int _tmain(int argc, _TCHAR* argv[])
{
    char temp[20]; 
   _CrtSetReportMode(_CRT_WARN, _CRTDBG_MODE_FILE);
   _CrtSetReportFile( _CRT_WARN, _CRTDBG_FILE_STDERR );   

    test();
    _CrtDumpMemoryLeaks();
    return 0;
}