说明：  Qt is a well-known cross-platform C++ visual development platform. Qt open source version provides the same functions as the commercial version. Qt 5 Development and Instance (2nd Edition) inherits the popular Qt 5 development and examples from the market.At the same time (Q1 5.4.0), QT application development is more systematic and more readable.This book is divided into two parts: The first part is the traditional Qt Widget programming. Each chapter introduces the Qt 5 application in a small example based on a brief introduction to the development environment.The development techniques of the program are generally introduced and explained through examples.