CPP-automatic-update-options / Debug a memory allocation

Inserting "#pragma once" preprocessor directive in the multiple files

"#pragma once" is a non-standard but widely supported preprocessor directive designed to cause the current source file to be included only once in a single compilation.

Using "#pragma once" allows the C preprocessor to include a header file when it is needed and to ignore an #include directive otherwise.

Some projects do not use this directive and this is not correct.

Adding #pragma once of multiple headers *.h files with Notepad++

	Find :  \A^.*?
	Replace with : #pragma once\n\r
	Files: *.h
	Search Mode: Regular Expression

Find memory leaks in multiple CPP files

Enable memory leak detection

The preceding techniques identify memory leaks for memory allocated using the standard CRT malloc function. If your program allocates memory using the C++ new operator, however, you may only see the filename and line number where operator new calls _malloc_dbg in the memory-leak report.

Inserting redifinition into *.cpp files

	Find :  \A^.*?
	Replace with : #ifdef _DEBUG\n\r#define new DBG_NEW\n\r#endif\n\r
	Files: *.cpp
	Search Mode: Regular Expression

Inserting redifinition for all *.cpp files

	Find :  \A^.*?
	Replace with : #ifdef _DEBUG\n\r#define DBG_NEW new ( _NORMAL_BLOCK , __FILE__ , __LINE__ )\n\r#else\n\r#define DBG_NEW new\n\r#endif\n\r
	Files: *.cpp
	Search Mode: Regular Expression

and then:

To enable all the debug heap functions, include the following statements in your C++ program

	#define _CRTDBG_MAP_ALLOC
	#include <stdlib.h>
	#include <crtdbg.h>

Adding heap malloc detection function of multiple *.cpp files with Notepad++

	Find :  \A^.*?
	Replace with : #define _CRTDBG_MAP_ALLOC\n\r#include <stdlib.h>\n\r#include <crtdbg.h>\n\r
	Files: *.cpp
	Search Mode: Regular Expression 

By results you see in all cpp files

	#define _CRTDBG_MAP_ALLOC
	#include <cstdlib>
	#include <crtdbg.h>

	#ifdef _DEBUG
		#define DBG_NEW new ( _NORMAL_BLOCK , __FILE__ , __LINE__ )
		// Replace _NORMAL_BLOCK with _CLIENT_BLOCK if you want the
		// allocations to be of _CLIENT_BLOCK type
	#else
		#define DBG_NEW new
	#endif

	#ifdef _DEBUG
		#define new DBG_NEW
	#endif

By manual setting

	#ifdef _DEBUG
	#undef DEBUG_NEW
	#define DEBUG_NEW new(__FILE__, __LINE__)
	#define _CRTDBG_MAP_ALLOC
	#define new DEBUG_NEW
	#undef THIS_FILE
	static char BASED_CODE THIS_FILE[] = __FILE__;
	#else
	#undef _CRTDBG_MAP_ALLOC
	#define DEBUG_NEW new
	#endif

When you run this code in the Visual Studio debugger, the call to _CrtDumpMemoryLeaks generates a report in the Output window.

For example :

		void main() {
		    .......
		    ,,,,,,, 
		    _CrtDumpMemoryLeaks();
		}

Get filename that does not contain the specified string

Visual Studio 2019 > Tools > Command Line > Developer PowerShell

ls ./*/*.cpp | Where{-not(select-string -path $_ -pattern "_CRTDBG_MAP_ALLOC" -Quiet)} | Select FullName

Find memory leaks into the custom DLL

To determine whether a memory leak has occurred in a section of code, you can take snapshots of the memory state before and after the section, and then use _ CrtMemDifference to compare the two states:

For example :

			_CrtMemState s1.s2,s3;


			BOOL APIENTRY DllMain( HMODULE hModule,
				   DWORD  ul_reason_for_call,
				   LPVOID lpReserved
			 )
			{
				switch (ul_reason_for_call)
				{
				case DLL_PROCESS_ATTACH:
				#ifdef _DEBUG	
					_CrtMemCheckpoint( &s1 );
				#endif	
				break;
				case DLL_THREAD_ATTACH:
				break;
				case DLL_THREAD_DETACH:
				break;
				case DLL_PROCESS_DETACH:
				#ifdef _DEBUG	
				   	 _CrtMemCheckpoint( &s2 );
						if ( _CrtMemDifference( &s3, &s1, &s2) 
				  			_CrtMemDumpStatistics( &s3 );
				#endif					   
				break;
				}
				return TRUE;
			}
			}

Use your own DllMain in MFC Dll's

If you try to write your own DllMain, you get a linker error saying "DllMain already defined".

To resolve this issue :

1. copy "dllmodul.cpp" from MFC source directory to your project directory and include it in your own project.

2 Modify dllmodul.cpp:

			CATCH(CMemoryException, e)
			{
				e->Delete();
			//	DELETE_EXCEPTION(e);
				pApp->ExitInstance();
				AfxWinTerm();
				goto Cleanup;       // Init Failed
			}

Adding breakpoint on memory leak detection items

1. If your app defines _CRTDBG_MAP_ALLOC, the memory-leak report looks like:

2. Start your debugging session:

3. Type _crtBreakAlloc in the Watch window. {,,MSVCR160d.dll}*__p__crtBreakAlloc()

Where MSVCR: C Runtime Library (CRL)

Number at the end of DLL file corresponds to the Visual Studio version number.

		90: Visual Studio 2008 (Version 9.0)
		100: Visual Studio 2010 (Version 10.0)
		110: Visual Studio 2012 (Version 11.0)
		120: Visual Studio 2013 (Version 12.0)
		140: Visual Studio 2015 (Version 14.0)
		150: Visual Studio 2017 (Version 15.0)
		160: Visual Studio 2019 (Version 16.0)

4. Double click on the -1 value, and enter the new allocation number that causes a user-defined breakpoint. After insert you see -1 ( current position )

5. After you set a breakpoint on a memory-allocation number, continue to debug. Make sure to run under the same conditions, so the memory-allocation number doesn't change.