sample calculator using simple gui tkinter in python

""" ***********************************************
programming Language :Python
Tool(IDE) used :Anaconda -> Spider
 date:03-07-2019
 created by:ANIL DURGAM

*****************************************************"""
# Python program to create a simple GUI

# calculator using Tkinter

# import everything from tkinter module

from tkinter import *


# globally declare the expression variable

expression = ""


# Function to update expressiom

# in the text entry box

def press(num):

 # point out the global expression variable

 global expression

 # concatenation of string

 expression = expression + str(num)
 # update the expression by using set method

 equation.set(expression)
# Function to evaluate the final expression

def equalpress():

 # Try and except statement is used

 # for handling the errors like zero

 # division error etc.

 # Put that code inside the try block

 # which may generate the error

 try:

  global expression

  # eval function evaluate the expression

  # and str function convert the result

  # into string

  total = str(eval(expression))



  equation.set(total)



  # initialze the expression variable

  # by empty string

  expression = ""

 # if error is generate then handle

 # by the except block

 except:

  equation.set(" error ")

  expression = ""

# Function to clear the contents

# of text entry box

def clear():

 global expression

 expression = ""

 equation.set("")

# Driver code

if __name__ == "__main__":

 # create a GUI window

 gui = Tk()
 # set the background colour of GUI window

 gui.configure(background="light green")
 # set the title of GUI window

 gui.title("Simple Calculator")
 # set the configuration of GUI window

 #gui.geometry("265x125")
 gui.geometry("360x180")

 # StringVar() is the variable class

 # we create an instance of this class

 equation = StringVar()
 # create the text entry box for

 # showing the expression .

 expression_field = Entry(gui, textvariable=equation)
 # grid method is used for placing

 # the widgets at respective positions

 # in table like structure .

 expression_field.grid(columnspan=4, ipadx=80)

 equation.set('enter your expression')

 # create a Buttons and place at a particular

 # location inside the root window .

 # when user press the button, the command or

 # function affiliated to that button is executed .

 button1 = Button(gui, text=' 1 ', fg='black', bg='white',

     command=lambda: press(1), height=1, width=7)

 button1.grid(row=2, column=0)



 button2 = Button(gui, text=' 2 ', fg='black', bg='white',

     command=lambda: press(2), height=1, width=7)

 button2.grid(row=2, column=1)



 button3 = Button(gui, text=' 3 ', fg='black', bg='white',

     command=lambda: press(3), height=1, width=7)

 button3.grid(row=2, column=2)



 button4 = Button(gui, text=' 4 ', fg='black', bg='white',

     command=lambda: press(4), height=1, width=7)

 button4.grid(row=3, column=0)



 button5 = Button(gui, text=' 5 ', fg='black', bg='white',

     command=lambda: press(5), height=1, width=7)

 button5.grid(row=3, column=1)



 button6 = Button(gui, text=' 6 ', fg='black', bg='white',

     command=lambda: press(6), height=1, width=7)

 button6.grid(row=3, column=2)



 button7 = Button(gui, text=' 7 ', fg='black', bg='white',

     command=lambda: press(7), height=1, width=7)

 button7.grid(row=4, column=0)



 button8 = Button(gui, text=' 8 ', fg='black', bg='white',

     command=lambda: press(8), height=1, width=7)

 button8.grid(row=4, column=1)



 button9 = Button(gui, text=' 9 ', fg='black', bg='white',

     command=lambda: press(9), height=1, width=7)

 button9.grid(row=4, column=2)



 button0 = Button(gui, text=' 0 ', fg='black', bg='white',

     command=lambda: press(0), height=1, width=7)

 button0.grid(row=5, column=0)



 plus = Button(gui, text=' + ', fg='black', bg='white',

    command=lambda: press("+"), height=1, width=7)

 plus.grid(row=2, column=3)



 minus = Button(gui, text=' - ', fg='black', bg='white',

    command=lambda: press("-"), height=1, width=7)

 minus.grid(row=3, column=3)



 multiply = Button(gui, text=' * ', fg='black', bg='white',

     command=lambda: press("*"), height=1, width=7)

 multiply.grid(row=4, column=3)



 divide = Button(gui, text=' / ', fg='black', bg='white',

     command=lambda: press("/"), height=1, width=7)

 divide.grid(row=5, column=3)



 equal = Button(gui, text=' = ', fg='black', bg='white',

    command=equalpress, height=1, width=7)

 equal.grid(row=5, column=2)



 clear = Button(gui, text='Clear', fg='black', bg='white',

    command=clear, height=1, width=7)

 clear.grid(row=5, column='1')



 # start the GUI

 gui.mainloop()



output: