Prerequisite : Tkinter Introduction, lambda function
Python offers multiple options for developing GUI (Graphical User Interface). Out of all the GUI methods, tkinter is most commonly used method. It is a standard Python interface to the Tk GUI toolkit shipped with Python. Python with tkinter outputs the fastest and easiest way to create the GUI applications. Creating a GUI using tkinter is an easy task.
To create a tkinter :
- Importing the module – tkinter
- Create the main window (container)
- Add any number of widgets to the main window
- Apply the event Trigger on the widgets.
Let’s create a GUI based simple calculator using Python Tkinter module, which can perform basic arithmatic operations addition, subtraction, multiplication and division.
Below is the implementation :
# 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" ) # 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 = 70 ) 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 = 'red' , command = lambda : press( 1 ), height = 1 , width = 7 ) button1.grid(row = 2 , column = 0 ) button2 = Button(gui, text = ' 2 ' , fg = 'black' , bg = 'red' , command = lambda : press( 2 ), height = 1 , width = 7 ) button2.grid(row = 2 , column = 1 ) button3 = Button(gui, text = ' 3 ' , fg = 'black' , bg = 'red' , command = lambda : press( 3 ), height = 1 , width = 7 ) button3.grid(row = 2 , column = 2 ) button4 = Button(gui, text = ' 4 ' , fg = 'black' , bg = 'red' , command = lambda : press( 4 ), height = 1 , width = 7 ) button4.grid(row = 3 , column = 0 ) button5 = Button(gui, text = ' 5 ' , fg = 'black' , bg = 'red' , command = lambda : press( 5 ), height = 1 , width = 7 ) button5.grid(row = 3 , column = 1 ) button6 = Button(gui, text = ' 6 ' , fg = 'black' , bg = 'red' , command = lambda : press( 6 ), height = 1 , width = 7 ) button6.grid(row = 3 , column = 2 ) button7 = Button(gui, text = ' 7 ' , fg = 'black' , bg = 'red' , command = lambda : press( 7 ), height = 1 , width = 7 ) button7.grid(row = 4 , column = 0 ) button8 = Button(gui, text = ' 8 ' , fg = 'black' , bg = 'red' , command = lambda : press( 8 ), height = 1 , width = 7 ) button8.grid(row = 4 , column = 1 ) button9 = Button(gui, text = ' 9 ' , fg = 'black' , bg = 'red' , command = lambda : press( 9 ), height = 1 , width = 7 ) button9.grid(row = 4 , column = 2 ) button0 = Button(gui, text = ' 0 ' , fg = 'black' , bg = 'red' , command = lambda : press( 0 ), height = 1 , width = 7 ) button0.grid(row = 5 , column = 0 ) plus = Button(gui, text = ' + ' , fg = 'black' , bg = 'red' , command = lambda : press( "+" ), height = 1 , width = 7 ) plus.grid(row = 2 , column = 3 ) minus = Button(gui, text = ' - ' , fg = 'black' , bg = 'red' , command = lambda : press( "-" ), height = 1 , width = 7 ) minus.grid(row = 3 , column = 3 ) multiply = Button(gui, text = ' * ' , fg = 'black' , bg = 'red' , command = lambda : press( "*" ), height = 1 , width = 7 ) multiply.grid(row = 4 , column = 3 ) divide = Button(gui, text = ' / ' , fg = 'black' , bg = 'red' , command = lambda : press( "/" ), height = 1 , width = 7 ) divide.grid(row = 5 , column = 3 ) equal = Button(gui, text = ' = ' , fg = 'black' , bg = 'red' , command = equalpress, height = 1 , width = 7 ) equal.grid(row = 5 , column = 2 ) clear = Button(gui, text = 'Clear' , fg = 'black' , bg = 'red' , command = clear, height = 1 , width = 7 ) clear.grid(row = 5 , column = '1' ) # start the GUI gui.mainloop() |
Output :
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