The dev environment in question consists of:
Windows 7
MinGW (g++)
CMake
Qt Creator
The problem is that Qt Creator, a lovely IDE as far as I can tell, does not display programs' command-line output. It seems to have its own proprietary debug pane, but it doesn't give me, for example, runtime errors. It just tells me that the program has failed and gives me the exit code. I'm using Creator only for its C++ capabilities, and not using Qt in any way, so the proprietary pane is useless to me.
So I ask this: Can something be done? Am I missing something really, stupidly obvious like a built-in command line? Or, if not, can I at least use some filthy and/or repulsive hack to get it to display the Windows command prompt upon running a program?
Last thing; I did do some research, and found a way to edit the Qt project file to display the prompt, but... I'm using CMake, not Qt projects. So that doesn't answer my question. If I can do something similar with CMakeLists.txt, that would be wonderful. But Google has failed me on that front, so I'm not holding out too much hope.
EDIT:
I'm specifically worried about runtime errors. cout and printf are rerouted to Qt Creator's window, so that's fine. I don't get runtime errors unless the debugger catches them, and the frequency of that is less than ideal.
Windows GUI programs don't have standard output.
In Windows there are two possible entry points in the standard runtime. The console one and the windows one. The console one will inherit console window from parent process or create a new one and connect the standard input/output/error streams to it, while the windows one will leave them unconnected unless they were explicitly redirected by the invoking process. A Qt application is (probably; you could have console Qt-Core application) a GUI application and Qt Creator (nor any other Windows IDE) does not redirect the output explicitly. Therefore the standard output is not open at all and the writes are being discarded.
However windows have separate logging facility for debugging purpose. This is what you see in the debug window. You can write to it using the native OutputDebugString API. I am sure you can also direct the Qt debug log there.
Note, that when it tells you the program has exited with status 0, it means the program ran, which in turn means it compiled successfully and thus there were no errors from g++. There may have been warnings, in which case you should see them in the appropriate other window. Compiler and program output are different things; the IDE does read the compiler output.
Related
One of my Win10 desktops has very odd problem with visual c++ compiler (vc142 toolchain/msvs2019, Win10): it opens new console window each time when c++ compiler (cl.exe) is started by any GUI app.
as the compiler is in the use by IDEs (e.g. VisualStudio, CLion, QtCreator etc) , it's very useless because output of the compiling can't be caught by callee (IDE) and IDEs don't show any compilation output , especially compile message in case of error. Obviously these IDEs do this indirectly , via build systems like msbuild or cmake . anyway , the problem is there.
So NMake or MSBuild can't be used correctly , because those ones run cl.exe in separate window. I have to run a build procedure from command line manually to see the error message.
the same toolchain can be used correctly on other Win10 hosts. I don't see the difference...
any idea why it 's happening and how to fix?
P.S. probably this is not a problem of cl but some windows terminal settings... or even security issues (I'm not an admin on that host)
For us, it was a corporate spyware program, BeyondTrust/PowerBroker for windows that was somehow making cl.exe misbehave.
PowerBroker basically takes over the UAC control and forces apps to run in privileged mode or non-privileged mode, etc. I'm not sure the mechanism but somehow it interfered with cl.exe writing to stderr, or ninja.exe's ability to redirect stderr to itself, or ninjas ability to pipe it somewhere or something.
Anyways, putting a whitelist rule in (or killing the beyondtrust service) made VSCode calling cmake calling ninja calling cl.exe behave properly.
EDIT: More details: cmake.exe, ninja.exe, and cmd.exe are the processes that need to get exempted from BeyondTrust's PRIVMAN to make cmake builds from VSCode function without popups.
I was having an issue with a C++ program where when I ran the .exe the program would run and my window for the program would open, but the console would be open on the desktop in the background. I did a google search and found that compiling with the -mwindows command as an argument, removes the console. Which it did. But I'm unsure of what it actually does and I am curious.
It behaves exactly the same as the /subsystem:windows switch described on MSDN.
Basically, it sets the entry point to WinMain (or wWinMain) instead of main (or wmain), which results in no console window and some Win32 startup code running to create the arguments passed to WinMain. As Neil says, it does not prevent or enable anything you can't do without it.
A similar switch is -municode to switch between main/WinMain and wmain/wWinMain, which is not mirrorred by the Microsoft tools. These seem to automagically select the one you use).
It says that your application is one using the Win32 API that doesn't need a console window. You use this option when you are writing Windows GUI applications, DLLs and the like, although a console window can be useful when debugging these kinds of applications. Even with this option, you can explicitly create a console window, should your application need one dynamically and, contrariwise, you can call Win32 GUI APIs from a console application.
In Code::Blocks 20.03 (uses the MinGW-W64 gcc compiler project) the project target ( bin/Release ) compiles with -mwindows and the project target ( bin/debug ) compiles without -mwindows. The debug target not only has debugging information in the executable, but it runs with the console window exposed in the background. This is 'highly' useful for debugging, since your app can write to the console debugging messages while your gui app is processing... like an active debugging log.
Obviously the console is ugly for release targets. In Code::Blocks the switch -mwindows is set indirectly in the Project properties under the 'build targets' the bin/debug build target is specified as console app, while the bin/release target is specified as gui app.
Back in the day (maybe eight years ago) there was a catch-22; -mwindows was necessary to link the Win32 api (but no console). If you wanted a console AND the Win32 api it didn't work easily; fortunately this is not an issue today... you can mix and match. I generally build my release targets without the console; and I build the debug targets with the console, and I use the console for debugging copiously.
marcus
I am developing my QT application on windows 10 . The development is complete (as for now).
After run the application in debug mode from QT-creator, I am trying to run the executable from the build directory. But it shows me an "Application Error" dialog with the following message:
The application was unable to start correctly (0xc000a200). Click OK
to close the application.
What is the problem and How to fix it ?!
The error codes are given to you in the error message for a reason. They don't mean anything to regular users, but we're programmers and we are the intended audience. Now that Google has been invented, you have absolutely no excuse for not taking the 5 seconds to Google the error code and see what it means.
In this case, 0xc000a200 is an error code that corresponds to STATUS_NOT_APPCONTAINER. The master list of COM error codes is in the Windows SDK headers, specifically ntstatus.h. If one looks this one up, one sees the following description:
This operation is only valid in the context of an app container.
Now, admittedly, once you get to this point, you may discover that you are in well over your head. You may not have any idea what an app container is, and certainly no clue about how to fix it. But at least then you would be able to ask a good question, which will go a long way to getting you a good answer.
But let's see if you can get lucky this time anyway. This error is most commonly encountered when an application that is not inside of an app container tries to load a DLL that is marked as being part of an app container. It is the linker that is responsible for marking a DLL as being or not being part of an app container, controlled by a series of options for whatever linker you're using. On Microsoft's linker, it is /APPCONTAINER:YES and /APPCONTAINER:NO that control this. I'm not sure what toolchain Qt Creator uses, but if it is not Microsoft's, this should at least get you started looking in the right place in that linker's documentation. Make sure that all DLLs used by your application are not being marked as part of an app container.
The option should be off by default for a regular C++ desktop application project, but it's possible that one of the DLLs started out life as part of a Windows Store app. Or it's possible that the switch just got thrown accidentally.
I had the same error, but the approved solution wasn't the cure. What I found is that I had installed the wrong Qt compiler support packages. For me it was Qt 5.9.1 on Windows 10 64 bit to use with Visual Studio 2017. When installing Qt I selected the "msvc2017 64-bit" option. Sound good, right? Wrong: what I wanted was the "UWP x64 (MSVC2017)".
I've been searching arround StackOverflow but seems I can't find the exact explanation for my problem:
I am running a GUI Application compiled under Visual Studio 2012. As it is a GUI application, sometimes it's quite hard to Debug it normally, so I need to printout some values while executing. I've done a couple of printf but the problem is that, as it is a GUI application there is no Console available while debugging it. I need to debug and have a Console to display these output values from printf. I know under CodeBlocks it is possible to do so, however the project is quite big to have to migrate everything to gcc CodeBlocks.
Could anyone tell me how to display such console or how to workaround the problem and have a similar result?
Thank you very much
Windows applicaton can't be both GUI and console.
There is a workaround however:
If you applicatop is based on MFC use TRACE macro.
Otherwise make your own wrapper around OutputDebugString function.
Both will output to Visual Studio's 'Output' pane when you launch our program under debugger
An of course you can always output diagnostic messages to good old log file.
I'm a hobbyist developer and have a background with Java (IDE of choice was Eclipse). I'm using Visual Studio Express 2010 and wanting to learn C++.
Few questions:
I create a "HelloWorld" in C++ and compiles/runs in VS/Windows. When I try to compile it under Linux/GCC, it obviously throws tons of errors. Default windows console project includes windows specific files; but if just create an "Empty Project" it throws tons of linker/build errors. What's the best practices here to keep my code portable?
Why is it creating 47 files for 8 lines of code?
How do you format code? You can do Edit->Format Selection, but the hotkeys don't work?
How do I output to VS's 'Output' Window? ( like eclipse does when you run a console java app )
It keeps reverting my "Project Location" to my "home directory" every time I restart. How do you change it? Is it a bug? Because it's Express edition?
Is there a way to keep it from switching to Debug view when it runs?
I create a "HelloWorld" in C++ and
compiles/runs in VS/Windows. When I
try to compile it under Linux/GCC, it
obviously throws tons of errors.
Default windows console project
includes windows specific files; but
if just create an "Empty Project" it
throws tons of linker/build errors.
What's the best practices here to keep
my code portable?
For portable code, avoid VS wizards entirely. Use Make/NMake if you're starting with rocks and sticks, or the portable build system of your preference (Ant, CMake, etc.) Some of these will spit out a VS solution/project file for you to use.
Why is it creating 47 files for 8
lines of code?
Wizards are magical like that.
How do you format code? You can do
Edit->Format Selection, but the
hotkeys don't work?
Ctrl-K Ctrl-F (under Edit, Advanced)
How do I output to VS's 'Output'
Window? ( like eclipse does when you
run a console java app )
Lookup OutputDebugString() for the debug window. Output window should get all cout/cerr output.
It keeps reverting my "Project
Location" to my "home directory" every
time I restart. How do you change it?
Is it a bug? Because it's Express
edition?
Probably hidden in options somewhere - don't know that one, sorry.
Is there a way to keep it from
switching to Debug view when it runs?
Launch using Ctrl+F5 to run without the debugger attached.
Have fun!
I create a "HelloWorld" in C++ and compiles/runs in VS/Windows. When I try to compile it under Linux/GCC, it obviously throws tons of errors. Default windows console project includes windows specific files; but if just create an "Empty Project" it throws tons of linker/build errors. What's the best practices here to keep my code portable?
It's fairly difficult to keep your code truly portable if you're writing Windows applications. Standard C++ will obviously work on either platform, but Linux can't run Windows applications, and vice versa. Remember that console applications are also considered Windows applications. They're not any more "pure" just because they are text-based, rather than graphical. Windows applications have their own entry point, different from the standard main function found in ANSI C++ (technically, main is still there, but it's hidden and called internally by the Windows libraries).
The best thing to do is not to link to any of the Windows headers. Unfortunately, you won't be very satisfied with the results. About all that you'll be able to generate is library code. You can't get a UI on the screen unless you use the Windows functions to do it.
An "Empty Project" is just what it says—empty. I assume the build errors are because you're trying to call functions that aren't defined anywhere. You'll find that you need to include windows.h to get off the ground, which instantly makes your code non-portable.
Why is it creating 47 files for 8 lines of code?
This is obviously an exaggeration; none of the wizards produce anywhere near that many code files. Especially not the "Empty Project", which doesn't create any at all.
A Win32 console application includes the following 5 files:
stdafx.h and stdafx.cpp — these files are used to enable "precompiled headers", meaning that Visual Studio will compile all of your headers once, and only recompile them when they change, rather than recompiling them each time you build the project. This used to provide enormous speed boosts, and still does on large projects. You probably don't need or care about this for small projects, but it's not a bad idea to get familiar with their usage if you're going to be developing in Visual Studio.
A targetver.h file, whose only purpose is to specify the earliest version of Windows that you want your application to run on. This is necessary because later versions of Windows add additional functionality that wasn't available in previous versions. Your app won't run if you link to functions or libraries that don't exist. Set this up once and then forget about it.
A <projectname>.cpp file, which is the implementation code for your application. This is pretty standard stuff—it includes the _tmain function, which is the entry point for a console app.
A ReadMe.txt file, which you can immediately delete. It contains some introductory information and describes the files that have been added to your project. (Yes, reading this yourself could have answered this question.)
A Win32 application would have a few more files, but most of the same ones as well. In particular, you'll see a resource file (with the extension .rc) that contains the icons, dialogs, bitmaps, cursors, etc. used in your program.
If you don't like this structure, you can either forgo the use of a wizard, or modify it yourself. There's nothing set in stone about it.
How do you format code? You can do Edit->Format Selection, but the hotkeys don't work?
Formatting code works fine. I'm not sure why people are telling you that Visual Studio doesn't support this, or that you'll need a third-party plug-in. There's no "Format Document" command as there is in C#, but the "Format Selection" command works just fine. The only difference is, you have to select something in order for it to be enabled.
The default keyboard extension for that command is CtrlK, Ctrl+F. It also works fine, right out of the box. My typical workflow is to hit Ctrl+A first to select all.
How do I output to VS's 'Output' Window? ( like eclipse does when you run a console java app )
I don't know what Eclipse does, nor do I know anything about Java. What do you want this to do? When and what things do you want to get written to the "Output" window? A console application will run in a console window, not in the "Output" window. That's not what it's for.
It's intended for debugging purposes. The OutputDebugString function is one way of utilizing it. The output of the standard cerr keyword should be automatically redirected to the "Output" window.
It keeps reverting my "Project Location" to my "home directory" every time I restart. How do you change it? Is it a bug? Because it's Express edition?
This isn't a bug, it's a feature. Visual Studio is designed for working with projects and solutions, not one-off code files. So by default, it prompts you to specify a project folder, a location to store your files. And what better place for the default location than your home folder?
If you don't like that location, you can change it. Under the "Tools" menu, select "Options". Expand the "Projects and Solutions" category, and click the "General" item. Then, change the path of the "Projects location" (the top textbox). Couldn't get much simpler than that.
Is there a way to keep it from switching to Debug view when it runs?
I frankly don't understand how this question makes any sense at all. When you run an application with the debugger attached, Visual Studio switches to a different window layout specifically optimized for debugging. I just answered a similar question. The upshot is that there's no way of telling Visual Studio to use the same window layout for both design and debug view, but I also can't imagine why you'd want to, either. Different things are useful, depending on what you're currently doing.
The two window layouts are customizable, and your changes are remembered. I've customized mine heavily from the defaults; it's very likely that your tastes vary as well. There are lots of great features, like the "Locals" window, which shows a listing of all the values of the local variables in scope at the point where you break into your program's execution.
Also remember that the default "Debug" and "Release" build configurations have nothing to do with whether or not Visual Studio automatically attaches the debugger to your application's process. If you want to start your app without the debugger attached, select "Start without Debugging" from the Debug menu, or press Ctrl+F5. There are lots of side effects to this though, and it's probably not what you wanted. Without the debugger attached, you lose most of what Visual Studio provides to you as an IDE. You might as well just run the app from Windows Explorer without even launching VS.
Finally, if you prefer Eclipse (or at least are already accustomed to its nuances and prefer not to learn Visual Studio's), you can still use it for C++ development. Download it here.
If you're just wanting to learn C++ and you don't necessarily care about the platform, I would probably avoid using Visual Studio to start with. Visual Studio provides some functionality for managing projects and builds, but honestly, I think you're better off learning how to manage code files and use the compiler on the command line first, then working up from there.
If you're on Windows, I'd recommend installing Cygwin and getting the GNU compiler tools through the Cygwin setup utility (gcc or g++).
This is a bit of an opinionated answer, but my experience with C++ on Windows leads me to believe that you'd be better served trying to learn C++ from more of a unix-like angle. Windows C++ adds a whole layer of crap that will just confuse you when you're getting started.