pyqt5编写一个简易计算器

from PyQt5.QtGui import *
from PyQt5.Qt import *
from PyQt5.QtCore import *
import sys,math,string

class Calculator(QWidget):
    def __init__(self,parent=None):
        QWidget.__init__(self,parent=parent)
        self.initUI()
        self.last=[]
    def initUI(self):
        list=['&','**','s','C',7,8,9,'+',4,5,6,'-',1,2,3,'*',0,'.','=','/']
        length=len(list)
        #创建动态按钮
        for i in range (length):
            self.button=QPushButton(str(list[i]),self)
            #将按钮的clicked信号与onButtonClick函数相连
            self.button.clicked.connect(self.onButtonClick)
            x=i%4
            y=int(i/4)
            self.button.move(x*40+10,y*40+100)
            self.button.resize(30,30)
        #创建文本框
        self.lineEdit=QLineEdit('',self)
        self.lineEdit.move(10,10)
        self.lineEdit.resize(150,70)
        self.setGeometry(200,200,170,300)
        self.setWindowTitle('计算器')
        self.show()
    def onButtonClick(self):
        t=self.lineEdit.text()#获取文本框文本
        new=self.sender().text()
        self.last.append(new)
        print(self.last)
        self.lineEdit.setText(t+new)
        if new== "=":
            result=eval(str(t))#计算
            self.lineEdit.setText(str(result))
        if new=='C':
            self.lineEdit.setText('')
        if new=='sqrt':
            self.lineEdit.setText('')
            result=math.sqrt(string.atof(t))
            self.lineEdit.setText(str(result))
        if new=="**":
            self.lineEdit.setText('')
            result=string.atof(t)**2
            self.lineEdit.setText(str(result))

app=QApplication(sys.argv)
w=Calculator()
w.show()
sys.exit(app.exec_())