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Detailed memory leak dumps from a console app

, 21 May 2002 164.2K 54
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How to get path and line number info for memory leaks, in a console app

Introduction

Finding memory leaks in a non-MFC app can be difficult because the debugger doesn't display path and line number info in the debug window. But, it's quite easy to enable that info. Here's how:

Step 1

Copy this to a file called LeakWatcher.h

#ifndef IMWATCHINGYOULEAK
#define IMWATCHINGYOULEAK

#include <crtdbg.h>

#ifdef _DEBUG
void* operator new(size_t nSize, const char * lpszFileName, int nLine)
{
    return ::operator new(nSize, 1, lpszFileName, nLine);
}
#define DEBUG_NEW new(THIS_FILE, __LINE__)

#define MALLOC_DBG(x) _malloc_dbg(x, 1, THIS_FILE, __LINE__);
#define malloc(x) MALLOC_DBG(x)

#endif // _DEBUG

#endif // #include guard

Step 2

Call _CrtDumpMemoryLeaks(); at the end of your program (or wherever you want to see outstanding memory allocations).

Steps 3...N

Add this to each of your source files (after your last #include) :

#include "LeakWatcher.h"

#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif

What does it do?

This does the same thing an MFC app does - it provides the path and line number of each allocation to the C-runtime allocation routines. Those routines store the path and line number for each allocation, and spit them out when you call _CrtDumpMemoryLeaks();. You should recognize that little chunk of code in step 3 from every source file that the AppWizard (and ClassWizard, mostly) has ever created.

Why not just use _CRTDBG_MAP_ALLOC?

#define _CRTDBG_MAP_ALLOC will provide file/line info for leaks caused by malloc, but for leaks with new, it ends up telling you that the leak occurred in crtdbg.h (because that's where MS defined their new) - not really useful.

Credits

This represents about ten minutes of searching through Microsoft's C runtime and MFC source files. So, all of the credit goes to MS. But, all of the blame goes to MS, too, for not making this part of the non-MFC headers. Anyway, have fun and be excellent to each other.

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here

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About the Author

Chris Losinger
Software Developer
United States United States
Chris Losinger is the president of Smaller Animals Software, Inc..

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Comments and Discussions

 
AnswerBetter way to avoid unfiled and unlided memory leaks is to Pin
steveb16-Aug-12 14:04
membersteveb16-Aug-12 14:04 
GeneralHit or Miss on the line number reporting... Pin
heckknow24-Dec-06 11:54
memberheckknow24-Dec-06 11:54 
GeneralRe: Hit or Miss on the line number reporting... Pin
smjones-home15-Mar-07 10:16
membersmjones-home15-Mar-07 10:16 
I get similar results. An earlier post suggests the new "new" is not getting called. Maybe that's what is happening.

-Steve
GeneralTwo Problems Pin
Andrew @ Neoteck4-May-05 21:36
sussAndrew @ Neoteck4-May-05 21:36 
GeneralRe: Two Problems Pin
Andrew @ Neoteck4-May-05 21:37
sussAndrew @ Neoteck4-May-05 21:37 
GeneralRe: Two Problems Pin
Chris Losinger5-May-05 0:59
memberChris Losinger5-May-05 0:59 
GeneralRe: Two Problems Pin
Andrew @ Neoteck5-May-05 13:34
sussAndrew @ Neoteck5-May-05 13:34 
GeneralRe: Two Problems Pin
Nosferatus22-Jul-05 5:53
memberNosferatus22-Jul-05 5:53 
GeneralRe: Two Problems Pin
Bob Stanneveld1-Feb-06 21:15
memberBob Stanneveld1-Feb-06 21:15 
QuestionWhere is memory leak from? Pin
morntide25-Feb-05 16:05
membermorntide25-Feb-05 16:05 
AnswerRe: Where is memory leak from? Pin
Nosferatus22-Jul-05 5:59
memberNosferatus22-Jul-05 5:59 
Questionisn't this better? Pin
Anonymous2-Feb-05 0:17
sussAnonymous2-Feb-05 0:17 
GeneralWhere to put _CrtDumpMemoryLeaks() for Dialog based applications... Pin
rbid21-Dec-04 21:16
sussrbid21-Dec-04 21:16 
GeneralTHIS_FILE redefinition Problems Pin
Anonymous5-Jan-04 16:37
sussAnonymous5-Jan-04 16:37 
GeneralRe: THIS_FILE redefinition Problems Pin
Anonymous5-Jan-04 17:23
sussAnonymous5-Jan-04 17:23 
GeneralRe: THIS_FILE redefinition Problems Pin
Chris Losinger6-Jan-04 1:32
memberChris Losinger6-Jan-04 1:32 
GeneralRe: THIS_FILE redefinition Problems Pin
Anonymous6-Jan-04 14:14
sussAnonymous6-Jan-04 14:14 
GeneralRe: THIS_FILE redefinition Problems Pin
Anonymous6-Jan-04 14:40
sussAnonymous6-Jan-04 14:40 
GeneralRe: THIS_FILE redefinition Problems Pin
Chris Losinger6-Jan-04 14:53
memberChris Losinger6-Jan-04 14:53 
GeneralRe: THIS_FILE redefinition Problems Pin
Anonymous7-Jan-04 3:11
sussAnonymous7-Jan-04 3:11 
GeneralRe: THIS_FILE redefinition Problems Pin
Chris Losinger7-Jan-04 3:39
memberChris Losinger7-Jan-04 3:39 
GeneralRe: THIS_FILE redefinition Problems Pin
Anonymous7-Jan-04 4:34
sussAnonymous7-Jan-04 4:34 
GeneralRe: THIS_FILE redefinition Problems Pin
Anonymous7-Jan-04 4:39
sussAnonymous7-Jan-04 4:39 
Generalspecialized &quot;new&quot; is never called Pin
blizzymadden25-Nov-03 12:46
memberblizzymadden25-Nov-03 12:46 
GeneralLink Errors Pin
Christian Cheney19-Nov-02 5:59
sussChristian Cheney19-Nov-02 5:59 

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