C + + memory leak detection supplements

In the MFC development environment, when the run exits, Visual Studio prompts for a memory leak in the Output window. You can also use MFC class CMemoryState to dynamically detect and output memory leak information.

In non-MFC frameworks, these functions need to be implemented with CRT functions.

1. Calling the _CrtDumpMemoryLeaks () function outputs the current memory leak in the Output window. If you add at the beginning of the program: _CrtSetDbgFlag (_CRTDBG_ALLOC_MEM_DF | _CRTDBG_LEAK_CHECK_DF);

statement, the CRT automatically calls the _CrtDumpMemoryLeaks function at each exit of the program, so that when the program terminates, all memory leaks are displayed in the Output window.

2. Using _CrtMemState structure Sentinel monitoring of memory leaks, example:

　//定义3个内存状态
　　　　　　　 _CrtMemState s1,s2,s3;

　　　　　　　 //记录开始的内存状态
　　　　　　　 _CrtMemCheckpoint( &s1 );

　　　　　　　 int　 *p = new int;

　　　　　　　 //记录结束时的内存状态
　　　　　　　 _CrtMemCheckpoint( &s2 );

　　　　　　　 //比较2个内存状态,并将差异保存到s3中
　　　　　　　 if( _CrtMemDifference( &s3, &s1, &s2 ) )
　　　　　　　 {
　　　　　　　　　　　 //输出内存泄漏信息
　　　　　　　　　　　 _CrtMemDumpAllObjectsSince( &s3 );
　　　　　　　 }

3. Redirect Output information. Memory leak Tip Default is output in the Output window, you can redirect its output position through _CrtSetReportMode. Example (redirect output to specified file):

　 CAtlFile　 hFile;
　　　　　　　 hFile.Create( _T("D:\\report.txt"), GENERIC_WRITE, FILE_SHARE_WRITE, CREATE_ALWAYS );
　　　　　　　 _CrtSetReportMode( _CRT_WARN, _CRTDBG_MODE_FILE );
　　　　　　　 _CrtSetReportFile( _CRT_WARN, hFile );

You can also redirect to form hints (forms with the Terminate, continue, ignore buttons), and the assertion is to output this form. You can also intercept messages by using the _CrtSetReportHook function before outputting to a specified destination. Such as:

_CrtSetReportHook (myreportingfunction);

The definition of myreportingfunction is as follows:

　int MyReportingFunction( int nReportType, char *szMsg, int *pRetVal )
{
　　　 *pRetVal = 0;
　　　 if( nReportType == _CRT_WARN )
　　　 {
　　　　　　　 AtlMessageBox( NULL, _U_STRINGorID( CA2T(szMsg)));
　　　 }
　　　 return 0;
}