Python code for GUI Calculator

Posted On February 3, 2023

This python code creates a basic GUI calculator. It will create a basic calculator GUI with four radiobuttons to choose the operator, two Entry widgets to input the numbers and a button to perform the calculation. The result will be displayed as a label.

import tkinter as tk

We import the tkinter library, which is the standard GUI library for Python.

def perform_calculation():
    # get the value of first and second number
    num1 = int(first_number_entry.get())
    num2 = int(second_number_entry.get())

The perform_calculation function retrieves the values of the first and second numbers from the Entry widgets and converts them to integers.

    # get the operator
    operator = operator_var.get()

The operator is retrieved from the operator_var variable, which is a StringVar object.

    # perform the calculation
    if operator == "+":
        result = num1 + num2
    elif operator == "-":
        result = num1 - num2
    elif operator == "*":
        result = num1 * num2
    elif operator == "/":
        result = num1 / num2
    else:
        result = "Invalid operator"

The calculation is performed based on the operator. If the operator is not one of the four supported operations (+, -, *, /), the function returns “Invalid operator”.

    # display the result
    result_label.config(text="Result: " + str(result))

The result is displayed in the result label. The config method is used to update the text of the label.

# create the main window
root = tk.Tk()
root.title("Calculator")
root.geometry("300x200")

We create the main window of the calculator application and set its title and size.

# create the first number label and entry
first_number_label = tk.Label(root, text="First Number")
first_number_label.pack()
first_number_entry = tk.Entry(root)
first_number_entry.pack()

We create a label and an Entry widget for the first number and arrange them on the window using the pack method.

# create the second number label and entry
second_number_label = tk.Label(root, text="Second Number")
second_number_label.pack()
second_number_entry = tk.Entry(root)
second_number_entry.pack()

We create a label and an Entry widget for the second number and arrange them on the window using the pack method.

# create the operator label and radiobuttons
operator_label = tk.Label(root, text="Operator")
operator_label.pack()

operator_var = tk.StringVar()

plus_button = tk.Radiobutton(root, text="+", variable=operator_var, value="+")
plus_button.pack()
minus_button = tk.Radiobutton(root, text="-", variable=operator_var, value="-")
minus_button.pack()
times_button = tk.Radiobutton(root, text="*", variable=operator_var, value="*")
times_button.pack()

Following is the entire code in one code block:

import tkinter as tk

# function for performing calculation
def perform_calculation():
    # get the value of first and second number
    num1 = int(first_number_entry.get())
    num2 = int(second_number_entry.get())

    # get the operator
    operator = operator_var.get()

    # perform the calculation
    if operator == "+":
        result = num1 + num2
    elif operator == "-":
        result = num1 - num2
    elif operator == "*":
        result = num1 * num2
    elif operator == "/":
        result = num1 / num2
    else:
        result = "Invalid operator"

    # display the result
    result_label.config(text="Result: " + str(result))

# create the main window
root = tk.Tk()
root.title("Calculator")
root.geometry("300x200")

# create the first number label and entry
first_number_label = tk.Label(root, text="First Number")
first_number_label.pack()
first_number_entry = tk.Entry(root)
first_number_entry.pack()

# create the second number label and entry
second_number_label = tk.Label(root, text="Second Number")
second_number_label.pack()
second_number_entry = tk.Entry(root)
second_number_entry.pack()

# create the operator label and radiobuttons
operator_label = tk.Label(root, text="Operator")
operator_label.pack()

operator_var = tk.StringVar()

plus_button = tk.Radiobutton(root, text="+", variable=operator_var, value="+")
plus_button.pack()
minus_button = tk.Radiobutton(root, text="-", variable=operator_var, value="-")
minus_button.pack()
times_button = tk.Radiobutton(root, text="*", variable=operator_var, value="*")
times_button.pack()
divide_button = tk.Radiobutton(root, text="/", variable=operator_var, value="/")
divide_button.pack()

# create the calculate button
calculate_button = tk.Button(root, text="Calculate", command=perform_calculation)
calculate_button.pack()

# create the result label
result_label = tk.Label(root, text="")
result_label.pack()

# start the main loop
root.mainloop()