Your browser does not seem to support JavaScript. As a result, your viewing experience will be diminished, and you have been placed in read-only mode.
Please download a browser that supports JavaScript, or enable it if it's disabled (i.e. NoScript).
Where can I download qrcodedialog.h file, ui_qrcodedialog.h and guiutil.h files to include in my program.
Are they part of some library? Then you need to get that lib. They are almost surely not in stock Qt packages.
From filename I would guess you're looking for QZXing library, but it is just a guess.