step-by-step installation of QT

[Kubani]

Hello all,

I have two questions.

1- I’ve a good experience in C++ so I decided to start the Qt. I downloaded below files from (http://qt-project.org/downloads)

Qt 5.3.0 for Windows 32-bit (MinGW 4.8.2, OpenGL, 734 MB) (Info)
Qt 5.3.0 for Windows 32-bit (VS 2012, OpenGL, 616 MB) (Info)

And my machine in Windows 7 Ultimate x86. And also I’ve used MS visual studio 2012 for C++ programming till now. So I have it installed on my machine.
Now how to install Qt by those two files? Is there anything else apart from those files to be downloaded and installed?

2- My purpose of using Qt is to create apps (for example for Windows or other OSes) when people order them for themselves. For example one shopkeeper may come before me and order an app for selling, supply, accounting and so on for his/her shop. OK, I create that app but I don’t want to give him/her its source code. I want to give only the installable version of the app or its .exe so that that person can work with it. Is this possible when using free (open source) version of Qt?

PS: I’m so novice in Qt so that I even haven’t seen its environment so far!

[helios]

OK, I create that app but I don’t want to give him/her its source code. I want to give only the installable version of the app or its .exe so that that person can work with it. Is this possible when using free (open source) version of Qt?

Yes, you can license Qt under the LGPL or GPL. The LGPL allows linking to non-GPL code. Changes made to the library itself must be made public, though.
In other words, you can develop closed source applications that use Qt, but you can't closed source changes to Qt without a commercial license.

[admkrk]

Don't install both, I'd suggest the first one. The VS one uses the VS compiler, but for debugging support you also have to install the Windows SDK. The MinGW one uses the GCC compiler and you won't have any problems debugging. Nothing else to install or link if you go that route. There is also a plugin for VS, but you are better off using Creator. The only thing I miss from VS is being able to indent or comment out blocks of code all at once.

[Kubani]

@helios:
What do you mean by "you can't close source changes to Qt without a commercial license"?
What if I develop an app with Qt and don't give the source changes to the Qt Project/company?

[helios]

There was a typo there. "You can't [make] closed source changes to Qt without a commercial license." If you modify the library itself and distribute it, those changes must be GPL.

[Kubani]

Consider this scenario:
Someone install the free version of Qt. And uses it and develop one app then doesn't send the source code to Qt and keeps it himself and sells the app. What will happen for he?

[abhishekm71]

@khoshtip
Following is just an idea but you are strongly suggested to consult a lawyer to check-out the details.

To put it simply, for most applications, if you build your exe file such that it links with Qt libraries dynamically (through DLL files) at run time, then you abide by the LGPL licence. You are allowed to distribute your application without your own source code.

However, if you want to create a single exe file that is 'statically' linked with Qt libraries, then you need to have a commercial licence.

[giblit]

Khoshtip he is talking about modifying the actual library of Qt not modifying the source code of a program that uses the Qt library. In other words yes you can sell closed source applications that use Qt library. Though I don't think you can statically link Qt. *Just read abhishekm71's message.

[Kubani]

Thank you very much guys.
I installed the first one and have in on my machine.