我有一个相对较旧的应用程序。通过一些小的更改，它几乎可以在Visual C ++ 2008中完美构建。我注意到的一件事是，我的“调试控制台”运行不正常。基本上，过去，我已经使用AllocConsole()过一个控制台，供调试输出使用。然后，我将使用freopen重定向stdout到它。这与C和C ++风格的IO完美配合。现在，它似乎仅适用于C风格的IO。将类似的东西重定向cout到分配有控制台的正确方法是什么AllocConsole()？这是曾经工作的代码：if(AllocConsole()) { freopen("CONOUT$", "wt", stdout); SetConsoleTitle("Debug Console"); SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), FOREGROUND_GREEN | FOREGROUND_BLUE | FOREGROUND_RED);}编辑：发生在我身上的一件事是，我可以制作一个自定义streambuf，其溢出方法使用C风格的IO编写，并std::cout用它替换默认的流缓冲区。但这似乎是一个解决方案。有没有合适的方法在2008年做到这一点？还是MS忽略了这一点？EDIT2：好的，所以我已经实现了上面阐述的想法。基本上看起来像这样：class outbuf : public std::streambuf {public: outbuf() { setp(0, 0); } virtual int_type overflow(int_type c = traits_type::eof()) { return fputc(c, stdout) == EOF ? traits_type::eof() : c; }};int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPTSTR lpCmdLine, int nCmdShow) { // create the console if(AllocConsole()) { freopen("CONOUT$", "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;}有没有人比强迫std::cout别人变得更好/更清洁的解决方案fputc？
3 回答
阿波罗的战车
TA贡献1862条经验 获得超6个赞
这是解决此问题的函数的最新版本：
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();
}
}
为了定义此功能，您需要以下一组包括：
#include <windows.h>
#include <io.h>
#include <fcntl.h>
#include <iostream>
简而言之，该函数将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。如文档中所述，AllocConsole为我们更改了这些过程句柄，因此所需要做的就是在AllocConsole之后调用该函数以更新运行时句柄，否则，我们将剩下初始化运行时时锁住的句柄。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);
此功能经过了多次修订，因此，如果您对历史信息或替代方法感兴趣，请检查对此答案的编辑。当前的答案是解决此问题的最佳方法，它具有最大的灵活性，并且可以在任何Visual Studio版本上使用。
Smart猫小萌
TA贡献1911条经验 获得超7个赞
我以答案形式发布了一个便携式解决方案，因此可以接受。基本上我取代cout的streambuf与一个被用c文件实现的I / O，其不结束被重新定向。感谢大家的投入。
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;
}
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