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Qt Overview

Qt is a complete C++ application development framework. It includes a class library and tools for cross-platform development and internationalization.

Design Goals

One of the key design goals behind Qt is to make cross-platform application programming intuitive, easy and fun.

Qt achieves this goal by abstracting low-level infrastructure functionality in the underlying window and operating systems, providing a coherent and logical interface that makes sense to programmers.

The Qt API and tools are consistent across all supported platforms (see below for details), enabling platform independent application development and deployment.

Qt applications run natively, compiled from the same source code, on all supported platforms:

  Qt/Windows  (Microsoft Windows XP, 2000, NT 4, Me/98/95)
  Qt/X11  (Linux, Solaris, HP-UX, IRIX, AIX, many other Unix variants)
  Qt/Mac  (Mac OS X)
  Qt/Embedded  (embedded Linux)

Business Benefits

Expanded Markets

You can use a surprisingly small amount of resources to realistically target Windows, Linux/Unix, Mac OS X, and embedded Linux platforms.

Short Learning Curves, Ease of Use

Qt developers only have to learn one API to write apps that run almost anywhere.

We have put considerable effort into making Qt as easy to use and intuitive as possible. Customers tell us that we succeeded: they find Qt programming simple and enjoyable. For the business this translates into more functionality and less maintenance without having to sacrifice quality.

More functionality, less work

The uniform cross-platform API lets programmers concentrate on value-adding innovation, instead of worrying about maintaining and administering infrastructure and interfaces for multiple versions of existing applications.

Platform Independence for Developers

In addition to having access to a very large widget-set, Qt developers only have to learn one API to write an application that will run on all major platforms. In addition, they can work on whichever platform they are most productive in.

Low Maintenance

By eliminating multiple source-trees, Qt eliminates the evils (and significant added costs) of maintaining and administering them. With one source, you have just one source to maintain, one source to administer, and a lot more time to do creative work.

Add Value, not Code

Qt lets programmers concentrate on adding value to the application code, instead of worrying about building, maintaining, and administering separate infrastructure and application codebases on multiple platforms.

Technical Benefits

True Platform Independence

Qt encapsulates the different platform-specific APIs of Unix, Windows, and Mac, and the APIs for file- handling, networking (Operations, Protocols), process-handling, threading, database access, etc. With Qt, ugly constructs such as #IFDEF (Win32) becomes a thing of the past.

Native Look and Feel

Qt GUIs are indistinguishable from native applications.

No Runtime Environment

Qt applications require no bulky runtime environment to be installed on the target systems, and hence there are no version conflicts to worry about. And on Windows, no X servers are required either.

High Performance

Qt requires no "virtual machines" or emulation layers. It writes directly to low-level graphics functions, just like native apps do. So Qt applications run at native speed.


Because Qt has been written to compile smoothly through multiple compilers, applications built with Qt are usually quite robust. Qt simplifies memory management by handling all deallocation of child widgets. Programmers need only concern themselves with top-level objects.

Easy integration with 3rd party libraries and products

Qt works well together with a host of other C++ libraries such as COIN, HOOPS3d, INT GeoToolkit, Open Inventor, Qwt and many others.

Migration from Microsoft Foundation Classes (MFC)

Qt offers an upgrade path for MFC applications. To read why and how, please click here.

Migration from Motif

Qt also offers an upgrade path for aging Motif applications, enabling updated look and feel on X11/Linux and Windows versions that don't need X servers. For more info, click here.

Extra widgets and components available

You can also get specialized widgets for Qt, such as KDAB Chart and ICS Table.

Related links

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