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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