头文件：DynamicDialog.h

#ifndef DYNAMICDIALOG_H
#define DYNAMICDIALOG_H#include <QtWidgets/QDialog>
#include <qlabel.h>
#include <qlineedit.h>
#include <qpushbutton.h>class DynamicDialog : public QDialog
{Q_OBJECTpublic:DynamicDialog(QWidget *parent = 0);~DynamicDialog();
private:QLabel *label1, *label2;QLineEdit *lineEdit;QPushButton *button;
private slots:void showArea();
};#endif // DYNAMICDIALOG_H

源文件：DynamicDialog.cpp

<span style="font-size:18px;">#include "dynamicdialog.h"
#include <qgridlayout.h>
const static double PI = 3.14159;
DynamicDialog::DynamicDialog(QWidget *parent): QDialog(parent)
{label1=new QLabel(this);label1->setText(tr("please input radius:"));lineEdit=new QLineEdit(this);label2=new QLabel(this);button=new QPushButton(this);button->setText(tr("Calculate Area"));QGridLayout *mainLayout=new QGridLayout(this);mainLayout->addWidget(label1,0,0);mainLayout->addWidget(lineEdit,0,1);mainLayout->addWidget(label2,1,0);mainLayout->addWidget(button,1,1);//connect(button,SIGNAL(clicked()),this,SLOT(showArea()));connect(lineEdit,SIGNAL(textChanged(QString)),this,SLOT(showArea()));}DynamicDialog::~DynamicDialog()
{}
void DynamicDialog::showArea()
{bool ok;QString tempStr;QString valueStr = lineEdit->text();int valueInt = valueStr.toInt(&ok);double area = valueInt*valueInt*PI;label2->setText(tempStr.setNum(area));
}</span>

2.运行结果

3.体会

如果之前一点都没有接触过UI设计，可以试试动态创建方法，否则，比较反感，开发周期长，很多动态创建完全没有必要。