求圆面积2

～风介～

code:

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

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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.     QObject::connect(lineEdit1,SIGNAL(textChanged(QString)),this,SLOT(showArea()));
    
17. 
    
18. 
    
19.     QGridLayout *mainLayout = new QGridLayout;
    
20.     mainLayout ->addWidget(label1,0,0);
    
21.     mainLayout ->addWidget(lineEdit1,0,1);
    
22.     mainLayout ->addWidget(label2,1,0);
    
23.     //mainLayout ->addWidget(button1,1,1);
    
24.     setLayout(mainLayout);
    
25. }
    
26. 
    
27. void CountCircleArea::showArea()
    
28. {
    
29.     bool ok;
    
30.     QString tempStr;
    
31.     QString valueStr = lineEdit1->text();
    
32.     int valueInt = valueStr.toInt(&ok);
    
33.     double area = valueInt*valueInt*PI;
    
34.     label2->setText((tempStr.setNum(area)));
    
35. }
    

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remark:
仅部分代码，具体参考：http://bbs.fishc.com/forum.php?mod=viewthread&tid=53147#lastpost