Python语言系统学习21：作品——简易计算器

原文链接：https://blog.csdn.net/weixin_45596188/article/details/103588042

一、程序运行效果

 在前面的学习中我们已掌握了对PyQt5和Qtdesigner的基本使用方法，今天我们来学习设计一个简易的计算器。对于用过Qt Designer 的人来说可以迅速掌握PyQt5 与Qt Designer 的配合使用的方法，对于初学者尽快掌握PyQt5的编程有很大的帮助。

二、开发流程

1、在Visual studio code中打开Qt Designer，如下图所示：

2、从工具栏区域选择拖动1个textEdit控件，1个List Widget控件，23个pushButton控件至设计窗口处。

3、修改各个控件的objectname,将它们改为统一的格式，如按钮“1”的objectname如下所示：

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4、对每行的按钮控件进行水平布局，每行按钮控件水平布局之后，再进行垂直布局。如下所示，先对每行进行水平布局：

5、将文件另存为，文件名命名为MainWindow.ui，如下图所示：

6、在Visual Studio Code中将MainWindow.ui文件转为MainWindow.py文件

三、源程序

# 系统包
import sys
from PyQt5 import QtCore, QtGui, QtWidgets
# 项目包
from Ui_MainWindow import Ui_Form

class CMainWindow(QtWidgets.QMainWindow, Ui_Form):
    def forge_link(self):
        self.b_0.clicked.connect(self.button_event(0))
        self.b_1.clicked.connect(self.button_event(1))    #前后连接槽绑定按键
        self.b_2.clicked.connect(self.button_event(2))
        self.b_3.clicked.connect(self.button_event(3))
        self.b_4.clicked.connect(self.button_event(4))
        self.b_5.clicked.connect(self.button_event(5))
        self.b_6.clicked.connect(self.button_event(6))
        self.b_7.clicked.connect(self.button_event(7))
        self.b_8.clicked.connect(self.button_event(8))
        self.b_9.clicked.connect(self.button_event(9))
                        
        self.b_add.clicked.connect(self.button_event('+'))
        self.b_sub.clicked.connect(self.button_event('-'))
        self.b_mul.clicked.connect(self.button_event('*'))
        self.b_div.clicked.connect(self.button_event('/'))
        self.b_pow.clicked.connect(self.button_event('**'))
        self.b_bra_l.clicked.connect(self.button_event('('))
        self.b_bra_r.clicked.connect(self.button_event(')'))
        self.b_mod.clicked.connect(self.button_event('%'))
        self.b_pai.clicked.connect(self.button_event('3.1415926535'))
        self.b_pt.clicked.connect(self.button_event('.'))
        self.b_del.clicked.connect(self.delete_event)
        self.b_clc.clicked.connect(self.clear_event)
        self.b_eq.clicked.connect(self.calc_complish)
        
    def __init__(self, parent = None):
        super(CMainWindow, self).__init__(parent)
        self.setupUi(self)
        self.setWindowTitle('简易计算器')
        self.forge_link()   #连接槽函数

        #主窗体设置
        self.show()
    def button_event(self,arg):
        global e_view       #全局变量
        e_view=self.e_view
        def fun():      #返回一个自定义的槽函数
            global e_view
            txt = e_view.toPlainText()
            e_view.setText(txt + str(arg))
        return fun

    def calc_complish(self):
        txt=self.e_view.toPlainText()
        ans=''
        try:                         #检测是否是正常计算 
            ans=str(eval(txt))
        except BaseException:
            ans='MathError'
        self.clear_event()
        self.e_view.setText(ans)
        self.l_hist.addItem(txt+'='+ans)
        
    def clear_event(self):
        self.e_view.setText('')
        
    def delete_event(self):
        txt = self.e_view.toPlainText()
        txt=txt[:len(txt)-1]                #len为返回值，返回对象为txt字符
        self.e_view.setText(txt)
if __name__ == '__main__':
    app = QtWidgets.QApplication(sys.argv)
    MainWindow = CMainWindow()
    sys.exit(app.exec_())

def forge_link(self):
    self.b_0.clicked.connect(self.button_event(0))
    self.b_1.clicked.connect(self.button_event(1))   
    self.b_2.clicked.connect(self.button_event(2))
    self.b_3.clicked.connect(self.button_event(3))
    self.b_4.clicked.connect(self.button_event(4))        
    self.b_5.clicked.connect(self.button_event(5))        
    self.b_6.clicked.connect(self.button_event(6))        
    self.b_7.clicked.connect(self.button_event(7))        
    self.b_8.clicked.connect(self.button_event(8))        
    self.b_9.clicked.connect(self.button_event(9))
                    
    self.b_add.clicked.connect(self.button_event('+'))        
    self.b_sub.clicked.connect(self.button_event('-'))        
    self.b_mul.clicked.connect(self.button_event('*'))        
    self.b_div.clicked.connect(self.button_event('/'))        
    self.b_pow.clicked.connect(self.button_event('**'))        
    self.b_bra_l.clicked.connect(self.button_event('('))        
    self.b_bra_r.clicked.connect(self.button_event(')'))        
    self.b_mod.clicked.connect(self.button_event('%'))        
    self.b_pai.clicked.connect(self.button_event('3.1415926535'))        
    self.b_pt.clicked.connect(self.button_event('.'))        
    self.b_del.clicked.connect(self.delete_event)        
    self.b_clc.clicked.connect(self.clear_event)        
    self.b_eq.clicked.connect(self.calc_complish)

def button_event(self,arg):   
    global e_view       #全局变量
    e_view=self.e_view
    def fun():      #返回一个自定义的槽函数
        global e_view
        txt = e_view.toPlainText()
        e_view.setText(txt + str(arg))
     return fun