【Python】GUI 练习1--利率计算器

import sys
from PyQt4.QtCore import *
from PyQt4.QtGui import *

class Form(QDialog):
    
    def __init__(self,parent=None):
    
        super(Form,self).__init__(parent)
        
        prinlabel=QLabel('Principal: ')
        ratelabel=QLabel('Rate: ')
        yearlabel=QLabel('Years: ')
        amountlabel=QLabel('Amount: ')
        self.numlabel=QLabel()
        
        self.prinspinbox=QDoubleSpinBox()
        self.ratespinbox=QDoubleSpinBox()
        self.yearcombobox=QComboBox()
        
        self.prinspinbox.setRange(1,10000000)
        self.prinspinbox.setValue(1000)
        self.prinspinbox.setPrefix("$ ")
        self.ratespinbox.setRange(0.0001,1000)
        self.ratespinbox.setValue(5)
        self.ratespinbox.setSuffix(" %")
        
        yearcon=[]
        for i in range(60):
            yearcon.append(str(i+1)+'  years')
        
        self.yearcombobox.addItems(yearcon)
        
        grid=QGridLayout()
        grid.addWidget(prinlabel,0,0)
        grid.addWidget(ratelabel,1,0)4
        grid.addWidget(yearlabel,2,0)
        grid.addWidget(amountlabel,3,0)
        
        grid.addWidget(self.prinspinbox,0,1)
        grid.addWidget(self.ratespinbox,1,1)
        grid.addWidget(self.yearcombobox,2,1)
        grid.addWidget(self.numlabel,3,1)
        
        self.setLayout(grid)
        self.setWindowTitle('Interest')
        
        self.connect(self.prinspinbox,SIGNAL('valueChanged(double)'),self.updataUi)
        self.connect(self.ratespinbox,SIGNAL('valueChanged(double)'),self.updataUi)
        self.connect(self.yearcombobox,SIGNAL('currentIndexChanged(int)'),self.updataUi)
        
    def updataUi(self):
        principal=self.prinspinbox.value()
        rate=self.ratespinbox.value()
        years=self.yearcombobox.currentIndex()+1
        amount=principal*((1+rate/100)**years)
        self.numlabel.setText('$ %0.2f' % amount)
        
app=QApplication(sys.argv)
form=Form()
form.show()
app.exec_()