Is there a possible way to attach the console to a GUI so that the user will be able to enter commands into the console from the GUI?
As long as the program is launched from the console, it can read and write from/to the console. There's nothing that makes a Java program "GUI" or "Console" except for the code.
If you want to always have a console regardless of how the program is launched, you could just code a frame to behave as one.
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I am attempting to use QTCreator's Memcheck tool to analyze the memory of a QT project, which is a dynamic library. It uses a QT Gui (QMainWindow) to allow the user to select a file, which is then processed, and then eventually returns to the mainwindow.
However, I cannot seem to use Memcheck properly.
When I select "Memcheck" and hit run, it instantly goes to "Analyzing memory" without ever letting the Gui pop up.
This is problematic. How can I get memcheck to work with this program?
I had two main issues:
1: Valgrind does not seem to play nice with QT Gui applications. It generates logs that are thousands of entries long for all the work QT is doing before it even gets to my application.
I had to make a separate, small non-GUI C++ program that would drive instead of the GUI application.
2: When trying to run from the command line, I needed to set an environment variable by using export. This needs to be the same as LD_LIBRARY_PATHS in QT Creator.
So I ran:
export LD_LIBRARY_PATH=X where X was the exact value I copied from LD_LIBRARY_PATHS in the variable from the QT Project.
Note: Running from the command line may have not be neccesary now that it isn't a GUI Application, memcheck might have passed just fine. Haven't tested since.
If I run a Qt application directly from the Windows command-line (cmd), it immediately returns back to the shell even as the GUI continues running; I assume it creates a second process before the parent exits.
If I run the Qt application indirectly though, from a batch file or Python script, it doesn't behave the same way; it blocks until the application actually exits:
Is this standard Qt behavior? I can't find any mention of it in the documentation or anywhere else. Can it be customized? I would prefer that the application always block when run from the command-line.
This is NORMAL Windows behavior.
In a console console programs are waited on. GUI programs are not. The rules are specified in start /?(mention of new behavior is NT4 to Windows 2000).
So Start /w c:\windows\notepad.
I have a small app that I'm trying to build against windows machines. The program creates an OpenVPN connection. If I build the program and run it it first opens a console as the program output. If I pass the -w parameter to pyinstaller to not build it with a console attached the program fails to run at all. It opens allright but the vpn connection is never created.
With the console everything works perfect.
I also have a basic logging for the application in place to see where my code might stop and nothing gets written. With console on my program spits out all kinds of logs.
I just don't know why my program could be performing perfectly with a console but doing nothing without one. Any ideas?
Gonna answer this myself. Make sure you don't print anything and also you redirect all stdout to a logger, file or whatever else instead of the console.
I was having a similar problem, but couldn't find any print/stdout statements going to console. I was using subprocess.Popen and redirecting stdout=subprocess.PIPE. I subsequently added stderr=subprocess.STDOUT and stdin=subprocess.PIPE and my program worked. This page (Python subprocess.call() fails when using pythonw.exe) on subprocess failures helped me get it working.
I'm using Ubuntu and Qt Creator 4
I have a .cpp program in the executable form (say abc.out) that I wish to run when I press a button. It contains a number of cin and cout, so I want it to run on a "terminal" (on Ubuntu) so that I am able to input and output values to it. How can I do that?
I've tried system() and
also,
QProcess p1;
p1.start(./abc.out);
Using QProcess, my executable runs but stops at the first cout. It runs on the application output screen in Qt Creator and not on terminal.
For example:
I see on application output:
enter name:
When I type the value and press enter here, it doesn't accept the value, but moves to the next line and allows me to type further.
I want to run this abc.out file on the terminal. Any ideas would be really helpful.
Do you mean Qt Creator 2.4? In any case, on the Projects tab, you should find the Run settings section and from there you can find a "Run in terminal" checkbox. You could also use a Custom Executable option and type there: gnome-terminal --command ./abc.out The exact details can vary a bit as I'm using Qt Creator 2.5.
This should work when launching from Qt Creator, but when you use your app outside the IDE, you need to launch it from terminal and not by double clicking the executable. To fix this, I can think of two ways:
Launch a terminal window from QtGui (something like QProcess::execute("gnome-terminal --command ./abc.out"); ), though the problem is different systems have different terminal names.
Provide a Qt input/text box yourself as part of your GUI which then forwards the user input to the executable (something like myqprocess.write(input_asked_from_user_by_QtGui); ). Here you probably need to know what information to ask the user beforehand. If you want to display the cout output of the started process, you can use the read method and friends of the QProcess.
From your question I assume that you are writing an application that launches other applications using QProcess. Thats fine, but if your subprocess is waiting for data from the standard input it will wait forever since you did not provide any data. The stdin of your parent application cannot be automatically guided to the subprocess. Imagine you are starting two processes from your main app. To which child process should the input go?
If you want to communicate with child processes, you must use the QIODevice methods of QProcess and send/read data from/to that application.
The only sensible solution is to launch the target application in a terminal. Whether your own code provides the terminal window or you reuse an existing terminal application is up to you.
I have a GUI program that opens a Windows console in a separate window to display output and accept user input. My development environment is Qt 4.7.1 with mingw. The console works fine, until I try to run the program in Qt's debugger (gdb); then, although AllocConsole succeeds, and GetStdHandle appears to return a valid handle (0x000000d8), any attempt to use the handle causes Windows error 6 (invalid handle).
So I can't debug my program. Which is a pain, because it has some serious bugs. The problem may be that gdb's console prevents me opening my own console; but then why do AllocConsole and GetStdHandle succeed? I upgraded to Qt Creator 2.0.94 (Qt 4.7.1), but it didn't help. Any ideas?
Update I have found that I can debug the program by running it without the debugger, and then attaching to it from Qt. Not ideal, but better than nothing.
Can't you use the standard output console, using
CONFIG += console
in the .pro file?
Hmm -- check this out:
A process can be associated with only one console, so the AllocConsole function fails if the calling process already has a console. A process can use the FreeConsole function to detach itself from its current console, then it can call AllocConsole to create a new console or AttachConsole to attach to another console.
Can you try running FreeConsole before you create yours?