Building a Simple Calculator with Python and Tkinter

Hello, aspiring Python developers! In this blog post, I'll walk you through creating a basic calculator application using Python's Tkinter library. This project is perfect for beginners who want to learn about graphical user interface (GUI) development in Python. We'll cover the entire code and explain each part step by step. By the end of this tutorial, you'll have a functional calculator and a better understanding of how to build GUI applications in Python. Let's get started!

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Here’s the GitHub link to the complete code for the calculator: GitHub Repository.

You can download the .exe file here: Download Executable

Code Explanation

Importing Tkinter

from tkinter import *

• Tkinter Import: We import all the necessary functions and classes from the Tkinter module to create our GUI.

Global Variable for Equation Text

equationText = ""

• Global Variable:equationText is a global variable that stores the current equation displayed on the calculator screen.

Button Press Function

def buttonPress(num):
    global equationText
    equationText = equationText + str(num)
    equationLabel.set(equationText)

• Function Definition:buttonPress appends the pressed button's value to equationText and updates the display.

Equals Function

def equals():
    global equationText
    try:
        total = str(eval(equationText))
        equationLabel.set(total)
        equationText = total
    except ZeroDivisionError:
        equationLabel.set("Arithmetic Error")
        equationText = ""
    except SyntaxError:
        equationLabel.set("Syntax Error")
        equationText = ""

• Function Definition:equals evaluates the current equation using eval(). It handles errors such as division by zero and syntax errors.

Clear Function

def clear():
    global equationText
    equationText = ""
    equationLabel.set(equationText)

• Function Definition:clear resets equationText and updates the display to be empty.

Setting Up the Window

window = Tk()
window.title("Calculator")
window.geometry("340x385")
window.resizable(width=FALSE, height=FALSE)

• Window Initialization: We create the main window, set its title, size, and make it non-resizable.

Display Label

equationLabel = StringVar()
label = Label(window, textvariable=equationLabel, font=("Arial Bold", 20), bg='white', relief=GROOVE, width=21, height=2, anchor='e', justify='right', padx=10)
label.pack()

• Label Creation: We create a label to display the equation and results, setting its text variable, font, background color, and other properties.

Button Frame

frames = Frame(window)
frames.pack()

• Frame Creation: We create a frame to organize the calculator buttons.

Calculator Buttons

button1 = Button(frames, text=1, height=2, width=7, font=35, command=lambda: buttonPress(1))
button1.grid(row=1, column=0)
button2 = Button(frames, text=2, height=2, width=7, font=35, command=lambda: buttonPress(2))
button2.grid(row=1, column=1)
...
clear = Button(frames, text='C', height=2, width=7, font=35, bg="#669bbc", command=clear)
clear.grid(row=4, column=0)

• Button Creation: We create buttons for numbers, operators, and special functions like clear and equals. Each button calls buttonPress with the appropriate value or function.

Main Loop

window.mainloop()

• Main Loop: We start the Tkinter event loop to keep the window open and responsive.

Conclusion

Creating this calculator was a great way to learn about Tkinter and GUI development in Python. We covered how to set up a window, create buttons, and handle user input. I hope you found this tutorial helpful and feel inspired to create your own GUI applications. Happy coding!