How To Find Memory Leaks

I have been working on VB, ASP for quite a long time. Very Recently (
>From past 1 month) I am managing a VC++ project. I am trying to use
the code which i downloaded from the internet to find the memory leak
in the VC++ dll which is causing the servers to crash. I am getting
the compilation error on this particular line

void * __cdecl operator new(unsigned int size,const char *file, int
line)

error C2059: syntax error : 'string' 
error C2091: function returns function 
error C2809: 'operator new' has no formal parameters 

which I don't know how to resolve. It would be a great help if any
body throw some light on this . Thank in advance

Below is the code which i cut and pasted from your article. 

Header File 
--------------- 
/ stdafx.h : include file for standard system include files, 
// or project specific include files that are used frequently, but 
// are changed infrequently 
// 
#if !defined(AFX_STDAFX_H__ADEF40E8_7DC0_4B4B_9B55_DC8B3C32A60E__INCLUDED_)
#define AFX_STDAFX_H__ADEF40E8_7DC0_4B4B_9B55_DC8B3C32A60E__INCLUDED_ 
#if _MSC_VER > 1000 
#pragma once 
#endif // _MSC_VER > 1000 
#define VC_EXTRALEAN // Exclude rarely-used stuff from Windows headers
#include <afxwin.h> // MFC core and standard components 
#include <afxext.h> // MFC extensions 
#include <afxdisp.h> // MFC Automation classes 
#include <list> 
#include <iostream> 
using namespace std ; 
int size; 
const char *file; 
int line; 
#include <afxdtctl.h> // MFC support for Internet Explorer 4 Common
Controls
#ifndef _AFX_NO_AFXCMN_SUPPORT 
#include <afxcmn.h> // MFC support for Windows Common Controls 
#endif // _AFX_NO_AFXCMN_SUPPORT 
#ifdef _DEBUG 
#define DEBUG_NEW new(__FILE__, __LINE__) 
#else 
#define DEBUG_NEW new 
#endif 
#define new DEBUG_NEW 

CPP File 
----------- 
// stdafx.cpp : source file that includes just the standard includes 
// Sample.pch will be the pre-compiled header 
// stdafx.obj will contain the pre-compiled type information 
#define __cdecl 
#include "stdafx.h" 
typedef struct { 
DWORD address; 
DWORD size; 
char file[64]; 
DWORD line; 
} ALLOC_INFO; 
typedef list<ALLOC_INFO*> AllocList; 
AllocList *allocList; 
void AddTrack(DWORD addr, DWORD asize, const char *fname, DWORD lnum) 
{ 
ALLOC_INFO *info; 
if(!allocList) { 
allocList = new(AllocList); 
} 
info = new(ALLOC_INFO); 
info->address = addr; 
strncpy(info->file, fname, 63); 
info->line = lnum; 
info->size = asize; 
allocList->insert(allocList->begin(), info); 
}; 
void RemoveTrack(DWORD addr) 
{ 
AllocList::iterator i; 
if(!allocList) 
return; 
for(i = allocList->begin(); i != allocList->end(); i++) 
{ 
if((*i)->address == addr) 
{ 
allocList->remove((*i)); 
break; 
} 
} 
}; 
void DumpUnfreed() 
{ 
AllocList::iterator i; 
DWORD totalSize = 0; 
char buf[1024]; 
if(!allocList) 
return; 
for(i = allocList->begin(); i != allocList->end(); i++) { 
sprintf(buf, "%-50s:\t\tLINE %d,\t\tADDRESS %d\t%d unfreed\n", 
(*i)->file, (*i)->line, (*i)->address, (*i)->size); 
OutputDebugString(buf); 
totalSize += (*i)->size; 
} 
sprintf(buf, "-----------------------------------------------------------\n");
OutputDebugString(buf); 
sprintf(buf, "Total Unfreed: %d bytes\n", totalSize); 
OutputDebugString(buf); 
}; 
#ifdef _DEBUG 
void * __cdecl operator new(unsigned int size,const char *file, int
line)
{ 
void *ptr = (void *)malloc(size); 
AddTrack((DWORD)ptr, size, file, line); 
return(ptr); 
}; 
inline void __cdecl operator delete(void *p) 
{ 
RemoveTrack((DWORD)p); 
free(p); 
}; 
#endif