如何使用Windows程序在C++中获得控制台输出？

Question

如果我有一个本机C++ Windows程序(即入口点是WinMain),我如何查看控制台函数的输出,如std :: cout？

Answer 1

查看将控制台I/O添加到Win32 GUI应用程序.这可以帮助您做您想做的事.

如果您没有或无法修改代码,请尝试此处找到的建议将控制台输出重定向到文件.

编辑:这里的线程坏死一点.我在第一次回答这个问题时,在早期的SO中,在非关联答案的(好)政策生效之前.我将重新发布原始文章中的代码,以期赎回我过去的罪过.

guicon.cpp - 控制台重定向功能

#include <windows.h>
#include <stdio.h>
#include <fcntl.h>
#include <io.h>
#include <iostream>
#include <fstream>
#ifndef _USE_OLD_IOSTREAMS
using namespace std;
#endif
// maximum mumber of lines the output console should have
static const WORD MAX_CONSOLE_LINES = 500;
#ifdef _DEBUG
void RedirectIOToConsole()
{
    int hConHandle;
    long lStdHandle;
    CONSOLE_SCREEN_BUFFER_INFO coninfo;
    FILE *fp;

    // allocate a console for this app
    AllocConsole();

    // set the screen buffer to be big enough to let us scroll text
    GetConsoleScreenBufferInfo(GetStdHandle(STD_OUTPUT_HANDLE), &coninfo);
    coninfo.dwSize.Y = MAX_CONSOLE_LINES;
    SetConsoleScreenBufferSize(GetStdHandle(STD_OUTPUT_HANDLE), coninfo.dwSize);

    // redirect unbuffered STDOUT to the console
    lStdHandle = (long)GetStdHandle(STD_OUTPUT_HANDLE);
    hConHandle = _open_osfhandle(lStdHandle, _O_TEXT);
    fp = _fdopen( hConHandle, "w" );
    *stdout = *fp;
    setvbuf( stdout, NULL, _IONBF, 0 );

    // redirect unbuffered STDIN to the console
    lStdHandle = (long)GetStdHandle(STD_INPUT_HANDLE);
    hConHandle = _open_osfhandle(lStdHandle, _O_TEXT);
    fp = _fdopen( hConHandle, "r" );
    *stdin = *fp;
    setvbuf( stdin, NULL, _IONBF, 0 );

    // redirect unbuffered STDERR to the console
    lStdHandle = (long)GetStdHandle(STD_ERROR_HANDLE);
    hConHandle = _open_osfhandle(lStdHandle, _O_TEXT);
    fp = _fdopen( hConHandle, "w" );
    *stderr = *fp;
    setvbuf( stderr, NULL, _IONBF, 0 );

    // make cout, wcout, cin, wcin, wcerr, cerr, wclog and clog
    // point to console as well
    ios::sync_with_stdio();
}

#endif
//End of File

guicon.h - 控制台重定向功能的接口

#ifndef __GUICON_H__
#define __GUICON_H__
#ifdef _DEBUG

void RedirectIOToConsole();

#endif
#endif

// End of File

test.cpp - 演示控制台重定向

#include <windows.h>
#include <iostream>
#include <fstream>
#include <conio.h>
#include <stdio.h>
#ifndef _USE_OLD_OSTREAMS
using namespace std;
#endif
#include "guicon.h"


#include <crtdbg.h>

int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPTSTR lpCmdLine, int nCmdShow)
{
    #ifdef _DEBUG
    RedirectIOToConsole();
    #endif
    int iVar;

    // test stdio
    fprintf(stdout, "Test output to stdout\n");
    fprintf(stderr, "Test output to stderr\n");
    fprintf(stdout, "Enter an integer to test stdin: ");
    scanf("%d", &iVar);
    printf("You entered %d\n", iVar);

    //test iostreams
    cout << "Test output to cout" << endl;
    cerr << "Test output to cerr" << endl;
    clog << "Test output to clog" << endl;
    cout << "Enter an integer to test cin: ";
    cin >> iVar;
    cout << "You entered " << iVar << endl;
    #ifndef _USE_OLD_IOSTREAMS

    // test wide iostreams
    wcout << L"Test output to wcout" << endl;
    wcerr << L"Test output to wcerr" << endl;
    wclog << L"Test output to wclog" << endl;
    wcout << L"Enter an integer to test wcin: ";
    wcin >> iVar;
    wcout << L"You entered " << iVar << endl;
    #endif

    // test CrtDbg output
    _CrtSetReportMode( _CRT_ASSERT, _CRTDBG_MODE_FILE );
    _CrtSetReportFile( _CRT_ASSERT, _CRTDBG_FILE_STDERR );
    _CrtSetReportMode( _CRT_ERROR, _CRTDBG_MODE_FILE );
    _CrtSetReportFile( _CRT_ERROR, _CRTDBG_FILE_STDERR);
    _CrtSetReportMode( _CRT_WARN, _CRTDBG_MODE_FILE );
    _CrtSetReportFile( _CRT_WARN, _CRTDBG_FILE_STDERR);
    _RPT0(_CRT_WARN, "This is testing _CRT_WARN output\n");
    _RPT0(_CRT_ERROR, "This is testing _CRT_ERROR output\n");
    _ASSERT( 0 && "testing _ASSERT" );
    _ASSERTE( 0 && "testing _ASSERTE" );
    Sleep(2000);
    return 0;
}

//End of File

Answer 2

像luke和Sev这样的答案的问题在于，它们不必要地创建了新FILE实例，然后这些实例会被泄露，并可能导致 CRT 清理代码中的调试断言。

freopen_s 真正需要的是：

FILE* fp = nullptr;
freopen_s(&fp, "CONIN$", "r", stdin);
freopen_s(&fp, "CONOUT$", "w", stdout);
freopen_s(&fp, "CONOUT$", "w", stderr);

您可能还想进行一些错误检查和清理。以下是我目前使用的完整解决方案。

重定向控制台标准 IO：

bool RedirectConsoleIO()
{
    bool result = true;
    FILE* fp;

    // Redirect STDIN if the console has an input handle
    if (GetStdHandle(STD_INPUT_HANDLE) != INVALID_HANDLE_VALUE)
        if (freopen_s(&fp, "CONIN$", "r", stdin) != 0)
            result = false;
        else
            setvbuf(stdin, NULL, _IONBF, 0);

    // Redirect STDOUT if the console has an output handle
    if (GetStdHandle(STD_OUTPUT_HANDLE) != INVALID_HANDLE_VALUE)
        if (freopen_s(&fp, "CONOUT$", "w", stdout) != 0)
            result = false;
        else
            setvbuf(stdout, NULL, _IONBF, 0);

    // Redirect STDERR if the console has an error handle
    if (GetStdHandle(STD_ERROR_HANDLE) != INVALID_HANDLE_VALUE)
        if (freopen_s(&fp, "CONOUT$", "w", stderr) != 0)
            result = false;
        else
            setvbuf(stderr, NULL, _IONBF, 0);

    // Make C++ standard streams point to console as well.
    ios::sync_with_stdio(true);

    // Clear the error state for each of the C++ standard streams.
    std::wcout.clear();
    std::cout.clear();
    std::wcerr.clear();
    std::cerr.clear();
    std::wcin.clear();
    std::cin.clear();

    return result;
}

释放控制台：

bool ReleaseConsole()
{
    bool result = true;
    FILE* fp;

    // Just to be safe, redirect standard IO to NUL before releasing.

    // Redirect STDIN to NUL
    if (freopen_s(&fp, "NUL:", "r", stdin) != 0)
        result = false;
    else
        setvbuf(stdin, NULL, _IONBF, 0);

    // Redirect STDOUT to NUL
    if (freopen_s(&fp, "NUL:", "w", stdout) != 0)
        result = false;
    else
        setvbuf(stdout, NULL, _IONBF, 0);

    // Redirect STDERR to NUL
    if (freopen_s(&fp, "NUL:", "w", stderr) != 0)
        result = false;
    else
        setvbuf(stderr, NULL, _IONBF, 0);

    // Detach from console
    if (!FreeConsole())
        result = false;

    return result;
}

调整控制台缓冲区的大小：

void AdjustConsoleBuffer(int16_t minLength)
{
    // Set the screen buffer to be big enough to scroll some text
    CONSOLE_SCREEN_BUFFER_INFO conInfo;
    GetConsoleScreenBufferInfo(GetStdHandle(STD_OUTPUT_HANDLE), &conInfo);
    if (conInfo.dwSize.Y < minLength)
        conInfo.dwSize.Y = minLength;
    SetConsoleScreenBufferSize(GetStdHandle(STD_OUTPUT_HANDLE), conInfo.dwSize);
}

分配一个新的控制台：

bool CreateNewConsole(int16_t minLength)
{
    bool result = false;

    // Release any current console and redirect IO to NUL
    ReleaseConsole();

    // Attempt to create new console
    if (AllocConsole())
    {
        AdjustConsoleBuffer(minLength);
        result = RedirectConsoleIO();
    }

    return result;
}

附加到家长的控制台：

bool AttachParentConsole(int16_t minLength)
{
    bool result = false;

    // Release any current console and redirect IO to NUL
    ReleaseConsole();

    // Attempt to attach to parent process's console
    if (AttachConsole(ATTACH_PARENT_PROCESS))
    {
        AdjustConsoleBuffer(minLength);
        result = RedirectConsoleIO();
    }

    return result;
}

从 WinMain 调用：

与 /SUBSYSTEM:Windows

int APIENTRY WinMain(
    HINSTANCE /*hInstance*/,
    HINSTANCE /*hPrevInstance*/,
    LPTSTR    /*lpCmdLine*/,
    int       /*cmdShow*/)
{
    if (CreateNewConsole(1024))
    {
        int i;

        // test stdio
        fprintf(stdout, "Test output to stdout\n");
        fprintf(stderr, "Test output to stderr\n");
        fprintf(stdout, "Enter an integer to test stdin: ");
        scanf("%d", &i);
        printf("You entered %d\n", i);

        // test iostreams
        std::cout << "Test output to std::cout" << std::endl;
        std::cerr << "Test output to std::cerr" << std::endl;
        std::clog << "Test output to std::clog" << std::endl;
        std::cout << "Enter an integer to test std::cin: ";
        std::cin >> i;
        std::cout << "You entered " << i << std::endl;

        std::cout << endl << "Press any key to continue..." << endl;
        _getch();

        ReleaseConsole();
    }

    return 0;
};

Answer 3

您也可以重新打开cout和cerr流以输出到文件.以下应该适用于此:

#include <iostream>
#include <fstream>

int main ()
{
    std::ofstream file;
    file.open ("cout.txt");
    std::streambuf* sbuf = std::cout.rdbuf();
    std::cout.rdbuf(file.rdbuf());
    //cout is now pointing to a file
    return 0;
}

Answer 4

如果您将程序的输出发送到文件或管道，例如

myprogram.exe > file.txt
myprogram.exe | anotherprogram.exe

或者您正在从另一个程序调用您的程序并通过管道捕获其输出，那么您不需要更改任何内容。即使入口点是WinMain.

但是，如果您在控制台或 Visual Studio 中运行程序，则输出将不会出现在控制台或 Visual Studio 的“输出”窗口中。如果您想查看“实时”输出，请尝试其他答案之一。

基本上，这意味着标准输出就像控制台应用程序一样工作，但它没有连接到您运行应用程序的控制台，而且似乎没有简单的方法可以做到这一点（此处提供的所有其他解决方案都连接输出到一个新的控制台窗口，当你运行你的应用程序时会弹出这个窗口，即使是从另一个控制台）。

Answer 5

实际上，有一个比迄今为止提出的任何解决方案都简单得多的解决方案。你的 Windows 程序将有一个 WinMain 函数，所以只需添加这个“虚拟”主函数

int main()
{
   return WinMain(GetModuleHandle(NULL), NULL, GetCommandLineA(), SW_SHOWNORMAL);
}

您现在可以像这样使用 MSVC 进行编译

cl /nologo /c /EHsc myprog.c
link /nologo /out:myprog.exe /subsystem:console myprog.obj user32.lib gdi32.lib

（您可能需要添加更多库链接）

当您运行程序时，任何内容printf都将写入命令提示符。

如果您使用 gcc (mingw) 为 Windows 编译，则不需要虚拟主函数，只需执行

gcc -o myprog.exe myprog.c -luser32 -lgdi32

（即避免使用-mwindows会阻止写入控制台的标志。当您创建最终的 GUI 版本时，该标志将很有用）如果使用更多的 Windows 功能，您可能需要指定更多的库）

Answer 6

在Windows桌面应用程序项目中，结合使用luke的答案和Roger的答案对我有用。

void RedirectIOToConsole() {

    //Create a console for this application
    AllocConsole();

    // Get STDOUT handle
    HANDLE ConsoleOutput = GetStdHandle(STD_OUTPUT_HANDLE);
    int SystemOutput = _open_osfhandle(intptr_t(ConsoleOutput), _O_TEXT);
    FILE *COutputHandle = _fdopen(SystemOutput, "w");

    // Get STDERR handle
    HANDLE ConsoleError = GetStdHandle(STD_ERROR_HANDLE);
    int SystemError = _open_osfhandle(intptr_t(ConsoleError), _O_TEXT);
    FILE *CErrorHandle = _fdopen(SystemError, "w");

    // Get STDIN handle
    HANDLE ConsoleInput = GetStdHandle(STD_INPUT_HANDLE);
    int SystemInput = _open_osfhandle(intptr_t(ConsoleInput), _O_TEXT);
    FILE *CInputHandle = _fdopen(SystemInput, "r");

    //make cout, wcout, cin, wcin, wcerr, cerr, wclog and clog point to console as well
    ios::sync_with_stdio(true);

    // Redirect the CRT standard input, output, and error handles to the console
    freopen_s(&CInputHandle, "CONIN$", "r", stdin);
    freopen_s(&COutputHandle, "CONOUT$", "w", stdout);
    freopen_s(&CErrorHandle, "CONOUT$", "w", stderr);

    //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 console or not.
    std::wcout.clear();
    std::cout.clear();
    std::wcerr.clear();
    std::cerr.clear();
    std::wcin.clear();
    std::cin.clear();

}

Answer 7

由于没有控制台窗口，所以这是不可能的困难。（每天学习新东西 - 我从来不知道控制台功能！）

您可以替换您的输出调用吗？我经常使用 TRACE 或 OutputDebugString 将信息发送到 Visual Studio 输出窗口。