Visual Studio 11 Development Guide (17) C ++ 11 Update-lambda expressions

Visual Studio may use lambda expressions (Forms of anonymous methods) in C ++ code since 2010 and more specifically in STL ). For example, if you look at the following code execution, when using these types of algorithms for_each, parallel_for, parallel_for_each, and so on.

1.std::deque<int> d1;2.    d1.push_back (2);3.    d1.push_back (1);4.    d1.push_back(3);5.    d1.push_back(0);6.    auto a=d1.begin ();7.    auto b=d1.end ();8.    std::sort(a,b);9.    10.    std::for_each (a,b,[](int i)11.    {12.            std::cout << i << std::endl;13.    });

 

Lambda starts to use two characters [] here to indicate that our capture syntax is different from that without local variables [] or [=] or that we capture all local variables by reference or backup respectively. Lambda does not capture any variables.

Now, this type of Lambda is implicitly converted to a function pointer. In other words, the old Win32 API is successfully called.
The example here is similar to createthreadpoolworkapi, pointing to the pointer parameter 1 of the function, and typing ptp_work_callback, which is obviously better than the original lambda.

 

1.PTP_POOL pool=CreateThreadpool(NULL);2.    TP_CALLBACK_ENVIRON cbEnviron;3.    InitializeThreadpoolEnvironment(&cbEnviron);4.    SetThreadpoolThreadMaximum (pool,4);    5.    BOOL bRet=SetThreadpoolThreadMinimum (pool,2);6.    7.    8.    PTP_WORK work=CreateThreadpoolWork([]( PTP_CALLBACK_INSTANCE Instance,PVOID Context,PTP_WORK Work)9.    {10.        11.        wprintf(L"Fait du boulot\n");12.    },NULL,&cbEnviron);13.    SubmitThreadpoolWork(work);    14.    WaitForThreadpoolWorkCallbacks(work,FALSE);15.    CloseThreadpoolWork(work);16.    CloseThreadpool(pool);

 

Another example API enumwindows, or we can use the old API to call the "Modern C ++ code" together

 

1.BOOL ret=EnumWindows ([](HWND hwnd,LPARAM lParam)->BOOL2.    {3.        const size_t MAX_SIZE=2048;4.        LPWSTR title=static_cast<LPWSTR>(_malloca(MAX_SIZE));        5.        if (title!=nullptr)6.        {7.            ZeroMemory (title,MAX_SIZE);8.            if (GetWindowTextLength (hwnd) >0)9.            {10.                GetWindowTextW  (hwnd,title,MAX_SIZE);11.                wprintf(L"%ls\n",title);12.                _freea(title);13.            }14.        }15.    16.        return TRUE;17.    },0);    

 

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