求圆面积1

～风介～

code:

1. 类名：CountCircleArea
   
2. 基于：QDialog
   
3. 备注：去掉勾选ui文件

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====================

1. //countcirclearea.h
   
2. 
   
3. #ifndef COUNTCIRCLEAREA_H
   
4. #define COUNTCIRCLEAREA_H
   
5. 
   
6. #include <QDialog>
   
7. 
   
8. 
   
9. QT_BEGIN_NAMESPACE
   
10. class QLabel;
    
11. class QLineEdit;
    
12. class QPushButton;
    
13. QT_END_NAMESPACE
    
14. 
    
15. 
    
16. class CountCircleArea : public QDialog
    
17. {
    
18.     Q_OBJECT
    
19. 
    
20. public:
    
21.     CountCircleArea(QWidget *parent = 0);
    
22. 
    
23. 
    
24. private:
    
25.     QLabel *label1,*label2;
    
26.     QLineEdit *lineEdit1;
    
27.     QPushButton *button1;
    
28. private slots:
    
29.     void showArea();
    
30. 
    
31. };
    
32. 
    
33. #endif // COUNTCIRCLEAREA_H
    

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1. //main.cpp
   
2. #include "countcirclearea.h"
   
3. #include <QApplication>
   
4. 
   
5. int main(int argc, char *argv[])
   
6. {
   
7.     QApplication a(argc, argv);
   
8.     CountCircleArea countcirclearea;
   
9.     countcirclearea.show();
   
10. 
    
11.     return a.exec();
    
12. }
    

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===========================

1. //countcirclearea.cpp
   
2. #include "countcirclearea.h"
   
3. #include <QtWidgets>
   
4. 
   
5. const static double PI = 3.1416;
   
6. 
   
7. CountCircleArea::CountCircleArea(QWidget *parent)
   
8.     : QDialog(parent)
   
9. {
   
10. 
    
11.     label1 = new QLabel(tr("Input Radius:"));
    
12.     label2 = new QLabel;
    
13.     lineEdit1 = new QLineEdit(tr("I Love FishC.com!"));
    
14.     button1 = new QPushButton("Display Area");
    
15.     QObject::connect(button1,SIGNAL(clicked()),this,SLOT(showArea()));
    
16. 
    
17. 
    
18.     QGridLayout *mainLayout = new QGridLayout;
    
19.     mainLayout ->addWidget(label1,0,0);
    
20.     mainLayout ->addWidget(lineEdit1,0,1);
    
21.     mainLayout ->addWidget(label2,1,0);
    
22.     mainLayout ->addWidget(button1,1,1);
    
23.     setLayout(mainLayout);
    
24. }
    
25. 
    
26. void CountCircleArea::showArea()
    
27. {
    
28.     bool ok;
    
29.     QString tempStr;
    
30.     QString valueStr = lineEdit1->text();
    
31.     int valueInt = valueStr.toInt(&ok);
    
32.     double area = valueInt*valueInt*PI;
    
33.     label2->setText((tempStr.setNum(area)));
    
34. }
    

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screenshot:

858418616

thank！