QT Creator Programming C + + first step, say "Hello world!"

This semester selected the computer Academy's "Digital Image processing", just and my image recognition project has a connection, the teacher said can not use MATLAB to do, this let me a did not learn C + + child paper to cry without tears.

Had to turn to the computer College of the big guy, self-taught C + +.

The big guy recommended me Qt Creator, I've only used VS, but listen to the big guy, in case I don't ask him. Download Link:

Http://mirrors.ustc.edu.cn/qtproject/archive/qt/5.7/5.7.0/qt-opensource-windows-x86-android-5.7.0.exe

Thanks to the computer Academy's old iron to provide me with the Qtcreator community version of the image download link, and then I started the bitter download process, QT is very small. Only a G, the installation does not take much effort, the direct default installation, select all the line.

The first time you write a C + + program, Qtcreator looks small and small, a little lighter than vs, a different style.

Once installed, create a project with Qtcreator.

Click on the top left file--new project-->QT Widgets application--> The following image is visible:

Create the path, then all defaults by default, next step.

Then you can write code in main.cpp.

I'm writing a classic code: output "Hello world!"

Here are the issues I encountered during the period:

Issue One: QT Creator compilation error: Cannot find file. Pro qt

Cause: QT Creator is not supported for directories larger than two spaces and Chinese-named catalogs .

Workaround: Modify the folder name and familiarize yourself with the English environment.

Question two: setgeometry:unable to set geometry 72x12+363+124 on qwidgetwindow/' Qlabelclasswindow '. Resulting geometry:120x12+363+124 (Frame:8, 8, 8, custom margin:0, 0, 0, 0, minimum size:0x0, maximum size:167772 15x16777215).

When writing Qlabel in Qt, this error is reported (should be a warning) if the size of the output interface is not specified.

When using the first paragraph of code:

#include "Mainwindow.h"
#include <QApplication>int main (intChar *argv[]) {    qapplication App (argc, argv);     Qlabel label ("Hello,World");    Label.show ();      return app.exec ();}

The output effect is a small, small block, as follows:

Then I changed the code and basically guessed the meaning of the Qlabel, and it was possible to define a variable.

 #include  mainwindow.h   "  #include  <qapplication># Include  <qlabel>int  Main (int  argc, char  *argv[]) {qapplication app (    ARGC, argv); Qlabel  *label=new  Qlabel ( " hello, World   " );     label->setgeometry (200,200,200,200);     Label->show ();  return   App.exec ();}  

This code is the choice of defining a label and then setting the contents of the Label object. The output box becomes larger.

C + +, here I come.

Good luck, September 7, 2017 on the first floor of the library.

QT Creator Programming C + + first step, say "Hello world!"