我有一个相对较旧的应用程序。通过一些小的更改，它几乎可以完美地与 Visual C++ 2008 一起构建。我注意到的一件事是我的“调试控制台”不能正常工作。基本上在过去，我使用 AllocConsole() 为我的调试输出创建一个控制台。然后我会使用 freopen 将 stdout 重定向到它。这与 C 和 C++ 风格的 IO 完美配合。

现在，它似乎只适用于 C 风格的 IO。将 cout 之类的内容重定向到分配有 AllocConsole() 的控制台的正确方法是什么？

这是以前工作的代码:

if(AllocConsole()) {
    freopen("CONOUT$", "wt", stdout);
    SetConsoleTitle("Debug Console");
    SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), FOREGROUND_GREEN | FOREGROUND_BLUE | FOREGROUND_RED);
}

编辑:我想到的一件事是我可以制作一个自定义的流缓冲区，其溢出方法使用 C 样式 IO 写入并替换 std::cout 的默认值流缓冲区。但这似乎是一种逃避。 2008年有没有合适的方法来做到这一点？或者这可能是 MS 忽略的东西？

EDIT2:好的，所以我已经实现了我上面阐述的想法。基本上是这样的:

class outbuf : public std::streambuf {
public:
    outbuf() {
        setp(0, 0);
    }

    virtual int_type overflow(int_type c = traits_type::eof()) {
        return fputc(c, stdout) == EOF ? traits_type::eof() : c;
    }
};

int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPTSTR lpCmdLine, int nCmdShow) {
    // create the console
    if(AllocConsole()) {
        freopen("CONOUT$", "w", stdout);
        SetConsoleTitle("Debug Console");
        SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), FOREGROUND_GREEN | FOREGROUND_BLUE | FOREGROUND_RED);  
    }

    // set std::cout to use my custom streambuf
    outbuf ob;
    std::streambuf *sb = std::cout.rdbuf(&ob);

    // do some work here

    // make sure to restore the original so we don't get a crash on close!
    std::cout.rdbuf(sb);
    return 0;
}

除了强制 std::cout 成为美化的 fputc 之外，任何人都有更好/更清洁的解决方案？

最佳答案

2018 年 2 月更新:

这是修复此问题的最新版本的函数:

void BindCrtHandlesToStdHandles(bool bindStdIn, bool bindStdOut, bool bindStdErr)
{
    // Re-initialize the C runtime "FILE" handles with clean handles bound to "nul". We do this because it has been
    // observed that the file number of our standard handle file objects can be assigned internally to a value of -2
    // when not bound to a valid target, which represents some kind of unknown internal invalid state. In this state our
    // call to "_dup2" fails, as it specifically tests to ensure that the target file number isn't equal to this value
    // before allowing the operation to continue. We can resolve this issue by first "re-opening" the target files to
    // use the "nul" device, which will place them into a valid state, after which we can redirect them to our target
    // using the "_dup2" function.
    if (bindStdIn)
    {
        FILE* dummyFile;
        freopen_s(&dummyFile, "nul", "r", stdin);
    }
    if (bindStdOut)
    {
        FILE* dummyFile;
        freopen_s(&dummyFile, "nul", "w", stdout);
    }
    if (bindStdErr)
    {
        FILE* dummyFile;
        freopen_s(&dummyFile, "nul", "w", stderr);
    }

    // Redirect unbuffered stdin from the current standard input handle
    if (bindStdIn)
    {
        HANDLE stdHandle = GetStdHandle(STD_INPUT_HANDLE);
        if(stdHandle != INVALID_HANDLE_VALUE)
        {
            int fileDescriptor = _open_osfhandle((intptr_t)stdHandle, _O_TEXT);
            if(fileDescriptor != -1)
            {
                FILE* file = _fdopen(fileDescriptor, "r");
                if(file != NULL)
                {
                    int dup2Result = _dup2(_fileno(file), _fileno(stdin));
                    if (dup2Result == 0)
                    {
                        setvbuf(stdin, NULL, _IONBF, 0);
                    }
                }
            }
        }
    }

    // Redirect unbuffered stdout to the current standard output handle
    if (bindStdOut)
    {
        HANDLE stdHandle = GetStdHandle(STD_OUTPUT_HANDLE);
        if(stdHandle != INVALID_HANDLE_VALUE)
        {
            int fileDescriptor = _open_osfhandle((intptr_t)stdHandle, _O_TEXT);
            if(fileDescriptor != -1)
            {
                FILE* file = _fdopen(fileDescriptor, "w");
                if(file != NULL)
                {
                    int dup2Result = _dup2(_fileno(file), _fileno(stdout));
                    if (dup2Result == 0)
                    {
                        setvbuf(stdout, NULL, _IONBF, 0);
                    }
                }
            }
        }
    }

    // Redirect unbuffered stderr to the current standard error handle
    if (bindStdErr)
    {
        HANDLE stdHandle = GetStdHandle(STD_ERROR_HANDLE);
        if(stdHandle != INVALID_HANDLE_VALUE)
        {
            int fileDescriptor = _open_osfhandle((intptr_t)stdHandle, _O_TEXT);
            if(fileDescriptor != -1)
            {
                FILE* file = _fdopen(fileDescriptor, "w");
                if(file != NULL)
                {
                    int dup2Result = _dup2(_fileno(file), _fileno(stderr));
                    if (dup2Result == 0)
                    {
                        setvbuf(stderr, NULL, _IONBF, 0);
                    }
                }
            }
        }
    }

    // Clear the error state for each of the C++ standard stream objects. We need to do this, as attempts to access the
    // standard streams before they refer to a valid target will cause the iostream objects to enter an error state. In
    // versions of Visual Studio after 2005, this seems to always occur during startup regardless of whether anything
    // has been read from or written to the targets or not.
    if (bindStdIn)
    {
        std::wcin.clear();
        std::cin.clear();
    }
    if (bindStdOut)
    {
        std::wcout.clear();
        std::cout.clear();
    }
    if (bindStdErr)
    {
        std::wcerr.clear();
        std::cerr.clear();
    }
}

为了定义这个函数，您需要以下一组包含:

#include <windows.h>
#include <io.h>
#include <fcntl.h>
#include <iostream>

简而言之，此函数将 C/C++ 运行时标准输入/输出/错误句柄与与 Win32 进程关联的当前标准句柄同步。如 the documentation 中所述, AllocConsole 为我们改变了这些进程句柄，所以只需要在 AllocConsole 之后调用这个函数来更新运行时句柄，否则我们将留下运行时初始化时锁定的句柄。基本用法如下:

// Allocate a console window for this process
AllocConsole();

// Update the C/C++ runtime standard input, output, and error targets to use the console window
BindCrtHandlesToStdHandles(true, true, true);

此功能已经过多次修订，因此如果您对历史信息或替代方案感兴趣，请查看对此答案的编辑。然而，当前的答案是这个问题的最佳解决方案，提供了最大的灵 active 并适用于任何 Visual Studio 版本。

关于c++ - 将 cout 重定向到 Windows 中的控制台，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/311955/