Visual Studio 2012 C ++标准输出 [英] Visual Studio 2012 C++ Standard Output

问题描述

在编译Win32应用程序时，fprintf（stdout / stderr）在Visual Studio中打印到哪里？我不断听到它的输出，但我看不到它！

Where does fprintf(stdout/stderr) print to in Visual Studio when compiling Win32 app? I keep hearing it goes to the output but I can't see it!.

在c ++中没有控制台窗口，打印输出日志的标准方式是什么？

Whats the standard way of printing to the output log without having a console window in c++?

推荐答案

如果你的程序与/ SUBSYSTEM：WINDOWS链接，你将不会看到控制台输出，除非你分配一个控制台。

If your program is linked with /SUBSYSTEM:WINDOWS you will not see the console output unless you allocate a console.

这里是用于分配控制台选项的代码。使用此方法，您不需要混乱链接器设置或创建WinMain。

Here is code for the allocate console option.With this method you should not need to mess with linker settings or create a WinMain.

static void OpenConsole()
{
    int outHandle, errHandle, inHandle;
    FILE *outFile, *errFile, *inFile;
    AllocConsole();
    CONSOLE_SCREEN_BUFFER_INFO coninfo;
    GetConsoleScreenBufferInfo(GetStdHandle(STD_OUTPUT_HANDLE), &coninfo);
    coninfo.dwSize.Y = 9999;
    SetConsoleScreenBufferSize(GetStdHandle(STD_OUTPUT_HANDLE), coninfo.dwSize);

    outHandle = _open_osfhandle((long)GetStdHandle(STD_OUTPUT_HANDLE), _O_TEXT);
    errHandle = _open_osfhandle((long)GetStdHandle(STD_ERROR_HANDLE),_O_TEXT);
    inHandle = _open_osfhandle((long)GetStdHandle(STD_INPUT_HANDLE),_O_TEXT );

    outFile = _fdopen(outHandle, "w" );
    errFile = _fdopen(errHandle, "w");
    inFile =  _fdopen(inHandle, "r");

    *stdout = *outFile;
    *stderr = *errFile;
    *stdin = *inFile;

    setvbuf( stdout, NULL, _IONBF, 0 );
    setvbuf( stderr, NULL, _IONBF, 0 );
    setvbuf( stdin, NULL, _IONBF, 0 );

    std::ios::sync_with_stdio();

}

如果您不想直接分配控制台，还可以通过更改子系统的链接器设置将子系统从/ SUBSYSTEM：windows更改为/ SUBSYSTEM：CONSOLE。记住当/ SUBSYSTEM：CONSOLE被启用时，gui仍然会像以前一样工作，但是窗口会为你和应用程序创建一个控制台窗口。

If you do not want to allocate a console directly you can also change the subsystem from /SUBSYSTEM:windows to /SUBSYSTEM:CONSOLE via changing the Subsystem of the linker settings. Remember when /SUBSYSTEM:CONSOLE is enabled the gui will still work the same as before but windows will create a console window for you along with your application.

在我的Qt代码，这是所有需要的。但是，当我在VisualStudio中尝试MFC并通过链接器设置将子系统设置为控制台。我得到以下错误：

In my Qt code that is all that is needed. However when I tried MFC in VisualStudio and set the subsystem to console via the linker setting. I got the following error:

1>------ Build started: Project: MFCApplication1, Configuration: Debug Win32 ------
1>  MFCApplication1.cpp
1>msvcrtd.lib(crtexe.obj) : error LNK2019: unresolved external symbol _main referenced in function ___tmainCRTStartup
1>X:\Test\VC.110\MFCTest\MFCApplication1\Debug\MFCApplication1.exe : fatal error LNK1120: 1 unresolved externals

入口点默认为main（）在控制台应用程序和WinMain在Windows应用程序。要解决这个问题，我必须在高级链接器设置的入口点设置中添加以下内容：wWinMainCRTStartup

This is caused by the entry point defaulting to main() in console applications and WinMain in windows applications. To fix this I had to add the following to the Entry Point setting of the Advanced Linker settings: "wWinMainCRTStartup"

在评论中，Ben Voigt建议使用另一种方法。使用editbin更改子系统不需要更改入口点。这是真的。我把删除的入口点和放回windows作为子系统构建测试应用程序，然后使用editbin更改子系统使用以下命令：

In the comments Ben Voigt suggested an alternate method. Using editbin to change the subsystem does not require a change in the entry point. This is indeed the case. I put removed the entry point and put windows back as the subsystem built the test application then used editbin to change the subsystem using the following command:

X:\Test\VC.110\MFCTest\MFCApplication1\Debug>editbin MFCApplication1.exe /SUBSYSTEM:CONSOLE
Microsoft (R) COFF/PE Editor Version 10.00.40219.01
Copyright (C) Microsoft Corporation.  All rights reserved.

我在控制台中得到了我预期的输出：

And I got the output I expected in the console:

X:\Test\VC.110\MFCTest\MFCApplication1\Debug>MFCApplication1.exe
Hello from a windows application!

注意：使用editbin方法，更新可执行文件。

Note: With the editbin method you need to renable this every time you update the executable.

最后在任何一个方法，一旦你有控制台printf或std :: cout将工作。例如在我的测试MFC应用程序中，我添加了以下行到CMFCApplication1App类的构造函数：

And finally on either method once you have the console printf or std::cout will work. For example in my test MFC application I added the following line to the constructor of the CMFCApplication1App class:

std::cout << "Hello from a windows application!" << std::endl;

这篇关于Visual Studio 2012 C ++标准输出的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！