licensing question

[tommy]

Hi all,

I have a general question about Qt licensing policy. I know that you can use Qt for free if you don't use it to make money or you provide full program code with your program. But what about when you BOTH make the program code publicly available and still make money by selling it. So, what if you fall between the two cases. On one hand I don't own the program because it becomes public, on the other hand I would get money for doing what I'm doing. Does anyone know if I need licensing for this situation?

Just out of curiosity, does anyone know how much a license costs if your sale volume is very small.

My last question is assuming that the license is expensive and I cannot afford to use Qt. In that case, what would be the second best C++ programming environment/library that is free (doesn't require licensing). I know that Qt is the best and I'd like to use it, but if it turns out too expensive to license, what would you recomend as an alternative.

Thanks a lot!

[ComaWhite]

You can do it. Just use LGPL as your option. But you must run Qt-4.5.0. Any version under 4.5.0 cannot be used with LGPL.

[tommy]

Thanks!

So LGPL will allow me to use Qt without the license if get money for my program but provide the buyer with full source code?

For example, if I have an istrument that is operated by software that I wrote in Qt, I could sell that instrument to someone and provide free software together with source (to go with that instrument) without obtaining the Qt license??

[bootsector]

Thanks!

So LGPL will allow me to use Qt without the license if get money for my program but provide the buyer with full source code?

For example, if I have an istrument that is operated by software that I wrote in Qt, I could sell that instrument to someone and provide free software together with source (to go with that instrument) without obtaining the Qt license??

With QT 4.5 (LGPL) you are free to release your software the way you want: free, proprietary, open source or closed source software!

The only time you NEED to provide the source code is when you modify QT itself. This way, you only need to provide the source code of the modified QT class (which is a good thing for the growing QT community)

Cheers,

bootsector

[zephid]

As written LGPL is the way to go, but you have to put into considerations, that your obligated to use Qt dynamiclly linked to your application, which means you have to give the end-user the choice to either compile their own copy of Qt and use it with your application.