Lost my QApplication

astroannie

Doing Qt C++ in Win 7.

I somehow am getting an error that I cannot open include file QApplicaiton -- I am following a YouTube tutorial. Help cannot find QApplicaiton either, so I suspect it has been superceded by something. How do I find out what? I'm a total novice, new to C++ and Qt. Also my knowledge of Windows esoterica is limited as well.

koahnig

@astroannie
Hi and welcome to devnet

You do not give enough details. However, it may be your virus checker playing a role. I have had similar cases that I could start my application and the next moment I could not. The executable was gone.

If this is not the case, you need to give some details about your setup and which tutorial you are following.

astroannie

Okay, the tutorial is C++ Qt Programming by VoidRealms -- I don't know how to get the nitty-gritty on which Qt I'm using except I downloaded it Tuesday so it's pretty new. (Help > About tells about QtCreator). And yes, I'm running Avast.

It's not my executable -- that one I can fix by logging out and logging back in again. This is an error where it says that it can't open QApplication Here's the code:

#include <QApplication>
#include <QLabel>

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    QLabel *label = new QLabel("Hello world");

    label->show();

    return app.exec();
}

... and here's the error:
C:\QtWorkspace\minimal\main.cpp:1: error: C1083: Cannot open include file: 'QApplications': No such file or directory

Is this more helpful?

mrjj

Hi
Do you have a project file ?
Its often called a .pro
in that file, you might need
QT += core gui

You can also test by selecting new from menu and create new GUI application.
(just next next it)
Then run it.
If that works, your Qt is fine.

astroannie

Sorry, it's QApplication -- no s -- I typed it instead of copy/paste. I learned though -- here's my .pro file

QT += core gui

SOURCES += \
    main.cpp

mrjj

ahh. ok. good catch :)

astroannie

I told Avast to exclude my workspace. It's still not being able to find the QApplication -- same message. I even tried restarting to no avail.

(I didn't realize you could copy/paste errors -- my old IDE was wonky about that). Here is what it really says, copy/pasted for your convenience:

C:\QtWorkspace\minimal\main.cpp:1: error: C1083: Cannot open include file: 'QApplication': No such file or directory

koahnig

@astroannie
You are using Qt creator as your new IDE?
You have the setup from your install process for Qt?

In Qt creator go to menu "Tools" -> "Options" -> "Build&Run" what can you see under the different tabs?
Are there some warnings?

astroannie

@koahnig
Okay, I looked.

My compiler is (not copy/pastable) Microsoft Visual C++ 10.0 (x86).

My Qt versions are 5.4.2 and 5.5.1 (both). Would removing one help?

The only thing I have warnings on is Kits -- which I didn't know I even had. They have little triangles with ! in them. One is Qt5.4.2 MSVC2010 OpenGL 32bit and the other is Qt5.5.1 MSVC2010 32-bit (default)

SGaist

Hi and welcome to devnet,

You are missing QT += widgets in your .pro file.

With Qt 5, the widgets have moved into their own module.

astroannie

Bless you sir, I regret that I can thumb you up but the once.

SGaist

No worries for that :)

Since you have it working now, please mark the thread as solved using the "Topic Tool" button so that other forum users may know a solution has been found :)