Add new file

第一次代码

+1.dialog.cpp
+1.dialog.cpp
+
+const static double PI=3.1416;
+#include "dialog.h"
+#include "ui_dialog.h"
+
+Dialog::Dialog(QWidget *parent) :
+    QDialog(parent),
+    ui(new Ui::Dialog)
+{
+    ui->setupUi(this);
+}
+
+Dialog::~Dialog()
+{
+    delete ui;
+}
+
+void Dialog::on_countBtn_clicked()
+{
+    bool ok;
+    QString tempStr;
+    QString valueStr=ui->radiusLineEdit->text();
+    int valueInt=valueStr.toInt(&ok);
+    double area=valueInt*valueInt*PI;//计算圆面积
+    ui->areaLabel_2->setText(tempStr.setNum(area));
+            
+}
+二、采用代a码完成
+1.dialog.cpp
+const static double PI=3.1416;
+#include<QGridLayout>
+#include "dialog.h"
+
+Dialog::Dialog(QWidget *parent)
+    : QDialog(parent)
+{
+    label1=new QLabel(this);
+    label1->setText(tr("请输入园的半径："));
+    lineEdit=new QLineEdit(this);
+    label2=new QLabel(this);
+    button=new QPushButton(this);
+    button->setText(tr("显示对应园的面积："));
+    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(lineEdit,SIGNAL(textChanged(QString)),this,SLOT(showArea()));
+
+}
+void Dialog::showArea()
+{
+    bool ok;
+    QString tempStr;
+    QString valueStr=lineEdit->text();
+    int valueInt=valueStr.toInt(&ok);
+    double area=valueInt*valueInt*PI;//计算圆面积
+    label2->setText(tempStr.setNum(area));
+
+}
+Dialog::~Dialog()
+{
+
+}
+2.dialog.h
+#include<QLabel>
+#include<QLineEdit>
+#include<QPushButton>
+#ifndef DIALOG_H
+#define DIALOG_H
+
+#include <QDialog>
+
+class Dialog : public QDialog
+{
+    Q_OBJECT
+
+public:
+    Dialog(QWidget *parent = 0);
+    ~Dialog();
+private:
+    QLabel*label1,*label2;
+    QLineEdit*lineEdit;
+    QPushButton*button;
+private slots:
+    void showArea();
+};
+
+#endif // DIALOG_H
+