Calculator

form.py

# -*- coding: utf-8 -*-

# Form implementation generated from reading ui file 'ui_xml\calc.ui'
#
# Created by: PyQt5 UI code generator 5.8.2
#
# WARNING! All changes made in this file will be lost!

from PyQt5 import QtCore, QtGui, QtWidgets

class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(340, 218)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.verticalLayout_2 = QtWidgets.QVBoxLayout(self.centralwidget)
        self.verticalLayout_2.setObjectName("verticalLayout_2")
        self.txt_res = QtWidgets.QLineEdit(self.centralwidget)
        self.txt_res.setObjectName("txt_res")
        self.verticalLayout_2.addWidget(self.txt_res)
        self.verticalLayout = QtWidgets.QVBoxLayout()
        self.verticalLayout.setObjectName("verticalLayout")
        self.gridLayout = QtWidgets.QGridLayout()
        self.gridLayout.setObjectName("gridLayout")
        self.btn_4 = QtWidgets.QPushButton(self.centralwidget)
        self.btn_4.setObjectName("btn_4")
        self.gridLayout.addWidget(self.btn_4, 1, 0, 1, 1)
        self.btn_3 = QtWidgets.QPushButton(self.centralwidget)
        self.btn_3.setObjectName("btn_3")
        self.gridLayout.addWidget(self.btn_3, 0, 2, 1, 1)
        self.btn_min = QtWidgets.QPushButton(self.centralwidget)
        self.btn_min.setObjectName("btn_min")
        self.gridLayout.addWidget(self.btn_min, 0, 3, 1, 1)
        self.btn_7 = QtWidgets.QPushButton(self.centralwidget)
        self.btn_7.setObjectName("btn_7")
        self.gridLayout.addWidget(self.btn_7, 2, 0, 1, 1)
        self.btn_8 = QtWidgets.QPushButton(self.centralwidget)
        self.btn_8.setObjectName("btn_8")
        self.gridLayout.addWidget(self.btn_8, 2, 1, 1, 1)
        self.btn_div = QtWidgets.QPushButton(self.centralwidget)
        self.btn_div.setObjectName("btn_div")
        self.gridLayout.addWidget(self.btn_div, 3, 3, 1, 1)
        self.btn_9 = QtWidgets.QPushButton(self.centralwidget)
        self.btn_9.setObjectName("btn_9")
        self.gridLayout.addWidget(self.btn_9, 2, 2, 1, 1)
        self.btn_6 = QtWidgets.QPushButton(self.centralwidget)
        self.btn_6.setObjectName("btn_6")
        self.gridLayout.addWidget(self.btn_6, 1, 2, 1, 1)
        self.btn_plu = QtWidgets.QPushButton(self.centralwidget)
        self.btn_plu.setObjectName("btn_plu")
        self.gridLayout.addWidget(self.btn_plu, 1, 3, 1, 1)
        self.btn_5 = QtWidgets.QPushButton(self.centralwidget)
        self.btn_5.setObjectName("btn_5")
        self.gridLayout.addWidget(self.btn_5, 1, 1, 1, 1)
        self.btn_1 = QtWidgets.QPushButton(self.centralwidget)
        self.btn_1.setObjectName("btn_1")
        self.gridLayout.addWidget(self.btn_1, 0, 0, 1, 1)
        self.btn_0 = QtWidgets.QPushButton(self.centralwidget)
        self.btn_0.setObjectName("btn_0")
        self.gridLayout.addWidget(self.btn_0, 3, 0, 1, 1)
        self.btn_mul = QtWidgets.QPushButton(self.centralwidget)
        self.btn_mul.setObjectName("btn_mul")
        self.gridLayout.addWidget(self.btn_mul, 2, 3, 1, 1)
        self.btn_2 = QtWidgets.QPushButton(self.centralwidget)
        self.btn_2.setObjectName("btn_2")
        self.gridLayout.addWidget(self.btn_2, 0, 1, 1, 1)
        self.btn_eq = QtWidgets.QPushButton(self.centralwidget)
        self.btn_eq.setAutoDefault(True)
        self.btn_eq.setDefault(True)
        self.btn_eq.setFlat(False)
        self.btn_eq.setObjectName("btn_eq")
        self.gridLayout.addWidget(self.btn_eq, 3, 1, 1, 1)
        self.btn_cl = QtWidgets.QPushButton(self.centralwidget)
        self.btn_cl.setObjectName("btn_cl")
        self.gridLayout.addWidget(self.btn_cl, 3, 2, 1, 1)
        self.verticalLayout.addLayout(self.gridLayout)
        self.verticalLayout_2.addLayout(self.verticalLayout)
        MainWindow.setCentralWidget(self.centralwidget)
        self.statusbar = QtWidgets.QStatusBar(MainWindow)
        self.statusbar.setObjectName("statusbar")
        MainWindow.setStatusBar(self.statusbar)

        self.retranslateUi(MainWindow)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)

    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
        self.btn_4.setText(_translate("MainWindow", "4"))
        self.btn_3.setText(_translate("MainWindow", "3"))
        self.btn_min.setText(_translate("MainWindow", "-"))
        self.btn_7.setText(_translate("MainWindow", "7"))
        self.btn_8.setText(_translate("MainWindow", "8"))
        self.btn_div.setText(_translate("MainWindow", "/"))
        self.btn_9.setText(_translate("MainWindow", "9"))
        self.btn_6.setText(_translate("MainWindow", "6"))
        self.btn_plu.setText(_translate("MainWindow", "+"))
        self.btn_5.setText(_translate("MainWindow", "5"))
        self.btn_1.setText(_translate("MainWindow", "1"))
        self.btn_0.setText(_translate("MainWindow", "0"))
        self.btn_mul.setText(_translate("MainWindow", "x"))
        self.btn_2.setText(_translate("MainWindow", "2"))
        self.btn_eq.setText(_translate("MainWindow", "="))
        self.btn_cl.setText(_translate("MainWindow", "Clear"))

form.ui

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>MainWindow</class>
 <widget class="QMainWindow" name="MainWindow">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>340</width>
    <height>218</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>MainWindow</string>
  </property>
  <widget class="QWidget" name="centralwidget">
   <layout class="QVBoxLayout" name="verticalLayout_2">
    <item>
     <widget class="QLineEdit" name="txt_res"/>
    </item>
    <item>
     <layout class="QVBoxLayout" name="verticalLayout">
      <item>
       <layout class="QGridLayout" name="gridLayout">
        <item row="1" column="0">
         <widget class="QPushButton" name="btn_4">
          <property name="text">
           <string>4</string>
          </property>
         </widget>
        </item>
        <item row="0" column="2">
         <widget class="QPushButton" name="btn_3">
          <property name="text">
           <string>3</string>
          </property>
         </widget>
        </item>
        <item row="0" column="3">
         <widget class="QPushButton" name="btn_min">
          <property name="text">
           <string>-</string>
          </property>
         </widget>
        </item>
        <item row="2" column="0">
         <widget class="QPushButton" name="btn_7">
          <property name="text">
           <string>7</string>
          </property>
         </widget>
        </item>
        <item row="2" column="1">
         <widget class="QPushButton" name="btn_8">
          <property name="text">
           <string>8</string>
          </property>
         </widget>
        </item>
        <item row="3" column="3">
         <widget class="QPushButton" name="btn_div">
          <property name="text">
           <string>/</string>
          </property>
         </widget>
        </item>
        <item row="2" column="2">
         <widget class="QPushButton" name="btn_9">
          <property name="text">
           <string>9</string>
          </property>
         </widget>
        </item>
        <item row="1" column="2">
         <widget class="QPushButton" name="btn_6">
          <property name="text">
           <string>6</string>
          </property>
         </widget>
        </item>
        <item row="1" column="3">
         <widget class="QPushButton" name="btn_plu">
          <property name="text">
           <string>+</string>
          </property>
         </widget>
        </item>
        <item row="1" column="1">
         <widget class="QPushButton" name="btn_5">
          <property name="text">
           <string>5</string>
          </property>
         </widget>
        </item>
        <item row="0" column="0">
         <widget class="QPushButton" name="btn_1">
          <property name="text">
           <string>1</string>
          </property>
         </widget>
        </item>
        <item row="3" column="0">
         <widget class="QPushButton" name="btn_0">
          <property name="text">
           <string>0</string>
          </property>
         </widget>
        </item>
        <item row="2" column="3">
         <widget class="QPushButton" name="btn_mul">
          <property name="text">
           <string>x</string>
          </property>
         </widget>
        </item>
        <item row="0" column="1">
         <widget class="QPushButton" name="btn_2">
          <property name="text">
           <string>2</string>
          </property>
         </widget>
        </item>
        <item row="3" column="1">
         <widget class="QPushButton" name="btn_eq">
          <property name="text">
           <string>=</string>
          </property>
          <property name="autoDefault">
           <bool>true</bool>
          </property>
          <property name="default">
           <bool>true</bool>
          </property>
          <property name="flat">
           <bool>false</bool>
          </property>
         </widget>
        </item>
        <item row="3" column="2">
         <widget class="QPushButton" name="btn_cl">
          <property name="text">
           <string>Clear</string>
          </property>
         </widget>
        </item>
       </layout>
      </item>
     </layout>
    </item>
   </layout>
  </widget>
  <widget class="QStatusBar" name="statusbar"/>
 </widget>
 <resources/>
 <connections/>
</ui>

main.py

import sys
from PyQt5.QtWidgets import QMainWindow, QApplication
from form_calc import Ui_MainWindow


class Form(QMainWindow, Ui_MainWindow):
    def __init__(self):
        super(__class__, self).__init__()
        self.setupUi(self)
        self.show()

        self.btn_0.clicked.connect(lambda: self.btn_clicked('0'))
        self.btn_1.clicked.connect(lambda: self.btn_clicked('1'))
        self.btn_2.clicked.connect(lambda: self.btn_clicked('2'))
        self.btn_3.clicked.connect(lambda: self.btn_clicked('3'))
        self.btn_4.clicked.connect(lambda: self.btn_clicked('4'))
        self.btn_5.clicked.connect(lambda: self.btn_clicked('5'))
        self.btn_6.clicked.connect(lambda: self.btn_clicked('6'))
        self.btn_7.clicked.connect(lambda: self.btn_clicked('7'))
        self.btn_8.clicked.connect(lambda: self.btn_clicked('8'))
        self.btn_9.clicked.connect(lambda: self.btn_clicked('9'))
        self.btn_min.clicked.connect(lambda: self.btn_clicked('-'))
        self.btn_plu.clicked.connect(lambda: self.btn_clicked('+'))
        self.btn_mul.clicked.connect(lambda: self.btn_clicked('*'))
        self.btn_div.clicked.connect(lambda: self.btn_clicked('/'))

        self.btn_eq.clicked.connect(lambda: self.eq_clicked())
        self.btn_cl.clicked.connect(lambda: self.txt_res.clear())

    def btn_clicked(self, text):
        old = self.txt_res.text()
        self.txt_res.setText(old + text)

    def eq_clicked(self):
        text = self.txt_res.text()
        try:
            res = eval(text)
            self.txt_res.setText(str(res))
        except:
            self.statusbar.showMessage('Error!')


if __name__ == '__main__':
    app = QApplication(sys.argv)
    form = Form()
    sys.exit(app.exec_())