2.QT字符串及一些基本操作

• mainwindow.h

   #ifndef MAINWINDOW_H
   #define MAINWINDOW_H
   
   #include <QMainWindow>
   
   namespace Ui {
   class MainWindow;
   }
   
   class MainWindow : public QMainWindow
   {
       Q_OBJECT
   
   public:
       explicit MainWindow(QWidget *parent = );
       ~MainWindow();
   
   private slots:
  19     void on_pushButton_clicked();
  20
  21     void on_pushButton_2_clicked();
  
   private:
       Ui::MainWindow *ui;
   };
   
   #endif // MAINWINDOW_H

• mainwindow.cpp

   #include "mainwindow.h"
   #include "ui_mainwindow.h"
   #include <QDebug>
   
   MainWindow::MainWindow(QWidget *parent) :
       QMainWindow(parent),
       ui(new Ui::MainWindow)
   {
       ui->setupUi(this);
   }
   
   MainWindow::~MainWindow()
   {
       delete ui;
   }
   
   void MainWindow::on_pushButton_clicked()
   {
  19     QString qstr1;
  20     QString qstr2;
  21     qstr1 = ui->lineEdit->text();
  22     qstr2 = ui->lineEdit_2->text();
  23     QString qstr3 ;
  24    // qstr3 = qstr1 + qstr2
  25     qstr3.sprintf("%s%d%s","123",45,"abc");
  26     qDebug() << qstr3 << endl;
  27     ui->textEdit->setText(qstr3);
   }
   
  30 void MainWindow::on_pushButton_2_clicked()
  31 {
  32     QString qstr3=QString("%1 is %2").arg("hello").arg(123);
  33     ui->textEdit->setText(qstr3);
  34 }