Python Kivy: Build a standard calculator application – Buttons functionality part 3

In the previous parts of this series, we covered setting up the Kivy environment and creating the basic layout for our standard calculator application. In this article, we will focus on the functionality of the buttons in the calculator app.

Button Functionality

Now that we have created the buttons for the calculator app, we need to implement their functionality. We will start by creating functions for each of the basic arithmetic operations: addition, subtraction, multiplication, and division.

Addition

To implement the addition functionality, we will create a function that adds the numbers entered by the user and displays the result on the calculator screen. We will then bind this function to the addition button using the Kivy syntax.

    def add(self):
        result = str(float(self.first_number) + float(self.second_number))
        self.display.text = result
    

Subtraction

Similar to the addition functionality, we will create a function for subtraction that subtracts the numbers entered by the user and displays the result on the calculator screen. We will then bind this function to the subtraction button using Kivy syntax.

    def subtract(self):
        result = str(float(self.first_number) - float(self.second_number))
        self.display.text = result
    

Multiplication

For multiplication, we will create a function that multiplies the numbers entered by the user and displays the result on the calculator screen. We will then bind this function to the multiplication button using Kivy syntax.

    def multiply(self):
        result = str(float(self.first_number) * float(self.second_number))
        self.display.text = result
    

Division

Finally, for division, we will create a function that divides the numbers entered by the user and displays the result on the calculator screen. We will then bind this function to the division button using Kivy syntax.

    def divide(self):
        if float(self.second_number) != 0:
            result = str(float(self.first_number) / float(self.second_number))
            self.display.text = result
        else:
            self.display.text = "Error: Division by zero"
    

Conclusion

With the basic arithmetic operations implemented, our standard calculator application is starting to take shape. In the next part of this series, we will add functionality for decimal point, clear, and equal buttons to complete the calculator app.