我有一個相對較舊的應用程序。通過一些小的更改，它幾乎可以在Visual C ++ 2008中完美構建。我注意到的一件事是，我的“調試控制臺”運行不正常?；旧希^去，我已經使用AllocConsole()過一個控制臺，供調試輸出使用。然后，我將使用freopen重定向stdout到它。這與C和C ++風格的IO完美配合?，F在，它似乎僅適用于C風格的IO。將類似的東西重定向cout到分配有控制臺的正確方法是什么AllocConsole()？這是曾經工作的代碼：if(AllocConsole()) { freopen("CONOUT$", "wt", stdout); SetConsoleTitle("Debug Console"); SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), FOREGROUND_GREEN | FOREGROUND_BLUE | FOREGROUND_RED);}編輯：發生在我身上的一件事是，我可以制作一個自定義streambuf，其溢出方法使用C風格的IO編寫，并std::cout用它替換默認的流緩沖區。但這似乎是一個解決方案。有沒有合適的方法在2008年做到這一點？還是MS忽略了這一點？EDIT2：好的，所以我已經實現了上面闡述的想法。基本上看起來像這樣：class outbuf : public std::streambuf {public: outbuf() { setp(0, 0); } virtual int_type overflow(int_type c = traits_type::eof()) { return fputc(c, stdout) == EOF ? traits_type::eof() : c; }};int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPTSTR lpCmdLine, int nCmdShow) { // create the console if(AllocConsole()) { freopen("CONOUT$", "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;}有沒有人比強迫std::cout別人變得更好/更清潔的解決方案fputc？
3 回答
阿波羅的戰車
TA貢獻1862條經驗 獲得超6個贊
這是解決此問題的函數的最新版本：
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();
}
}
為了定義此功能，您需要以下一組包括：
#include <windows.h>
#include <io.h>
#include <fcntl.h>
#include <iostream>
簡而言之，該函數將C / C ++運行時標準輸入/輸出/錯誤句柄與與Win32進程關聯的當前標準句柄同步。如文檔中所述，AllocConsole為我們更改了這些過程句柄，因此所需要做的就是在AllocConsole之后調用該函數以更新運行時句柄，否則，我們將剩下初始化運行時時鎖住的句柄?；居梅ㄈ缦拢?/p>
// 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);
此功能經過了多次修訂，因此，如果您對歷史信息或替代方法感興趣，請檢查對此答案的編輯。當前的答案是解決此問題的最佳方法，它具有最大的靈活性，并且可以在任何Visual Studio版本上使用。
Smart貓小萌
TA貢獻1911條經驗 獲得超7個贊
我以答案形式發布了一個便攜式解決方案，因此可以接受。基本上我取代cout的streambuf與一個被用c文件實現的I / O，其不結束被重新定向。感謝大家的投入。
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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