# Building a Simple Calculator Using Python and Tkinter

## Building a Simple Calculator using Python

Are you looking to build a simple calculator using Python? Python is an object-oriented and high-level programming language that is widely used by developers to build efficient applications.

Building a calculator can be a great way to start learning Python and to understand its syntax. In this article, we will walk you through the steps to build a simple calculator using Python.

## Syntax for creating the calculator

Before we dive into the steps to build the calculator, let’s discuss the syntax for creating it in Python. The first step is to create a function for each operation you want the calculator to perform, such as addition, subtraction, multiplication, and division.

You can then define the GUI components of the calculator using the Tkinter package, which provides a toolkit for creating graphical user interfaces (GUIs). These components include buttons, input fields, and labels, among others.

You will also need to define the layout and positioning of these components on the canvas.

## Steps to build the calculator

Now that you understand the syntax for building the calculator, let’s take a closer look at the steps involved.

### Step 1: Import the required packages

Begin by importing the required packages, including the Tkinter and math packages.

The Tkinter package provides the GUI components, while the math package provides the mathematical operations for the calculator. Example:

``````from tkinter import *
import math``````

### Step 2: Define the GUI canvas

Next, create a window for the GUI by defining the canvas. This canvas will house all of your GUI components, including the input fields, buttons, and labels.

### Example:

``````root = Tk()
root.title("Calculator")
canvas = Canvas(root, width=240, height=280)
canvas.pack()``````

### Step 3: Define the input fields and labels

You can then define the input fields and labels that will be displayed on the calculator. These fields will allow the user to input numbers and the calculator to display the results of each operation.

### Example:

``````input_field = Entry(canvas, width=20, font=('Arial',20))
canvas.create_window(50, 50, window=input_field)
output_label = Label(canvas, text="", font=('Arial', 20))
canvas.create_window(120, 150, window=output_label)``````

### Step 4: Define the calculation functions

As previously mentioned, you will also need to define the calculation functions for the calculator. For example, below is a function for adding two numbers.

### Example:

``````def add_function():
num1 = float(input_field.get())
num2 = float(output_label['text'])
result = num1 + num2
output_label.config(text=result)``````

### Step 5: Define the buttons

Lastly, you will need to create buttons for the calculator. These buttons should be associated with the respective calculation functions.

### Example:

``````add_button = Button(canvas, text="+", width=5, height=2, font=('Arial', 20), command=add_function)

## Importing the Tkinter Package and Creating the GUI Canvas

Before building the calculator, let’s first understand how to import the Tkinter package and create the GUI canvas.

### Importing the Tkinter package

To create a graphical user interface (GUI) using Python, you need to use a package called Tkinter. This package provides a toolkit that enables you to create windows, buttons, input fields, and various other GUI components.

To import Tkinter, simply type the following code before starting your program:

``from tkinter import *``

### You can also import specific components from the package by specifying their names:

``from tkinter import Button, Label, Entry``

### Creating the canvas

After importing the package, the next step is to create the canvas that will house all your GUI components. The canvas serves as a container for all the GUI components and provides a platform for you to display messages and receive user input.

To create the canvas, use the following code:

``````root = Tk() # initialize the window
root.title("My Calculator") # window title
canvas = Canvas(root, width=300, height=300) # canvas dimensions
canvas.pack() # add the canvas to the window``````

By default, the canvas is set to the top-left corner of the window. You can set the canvas position by adding the `x` and `y` coordinates in the `create_window()` function:

``canvas.create_window(150, 150, window=label)``

In the above example, the label is positioned at the coordinates `(150,150)` on the canvas.

## Conclusion

Building a simple calculator using Python can be a great way to start learning Python and to understand its syntax and GUI components. By following these steps and understanding the syntax involved, you should be able to build your own calculator in no time.

Good luck!

### 3) Creating the Entry Boxes

When creating a calculator using Python and the Tkinter package, entry boxes are necessary to allow the user to input values. These boxes will provide an interface for users to input the data that the calculator will process.

To create an entry box in Tkinter, use the following code:

``````entry_box = Entry(canvas, width=10, font=("Arial", 20))
entry_box.pack()``````

In the above example, `canvas` is the object that represents the canvas on which the GUI is displayed. The `width` parameter sets the width of the entry box in terms of the number of characters that can be displayed in it.

The `font` parameter sets the font used for the text displayed in the entry box. Once the entry box has been created, you may want to assign a default value to it.

To do this, use the `insert()` function as follows:

``entry_box.insert(0, "0")``

This will set the initial value of the entry box to 0. You can also set the entry box to be read-only.

This means that users won’t be able to type anything into the box. This can be useful for displaying results that users can’t change.

To create a read-only entry box, simply set the `state` parameter to `”readonly”`:

``entry_box = Entry(canvas, width=10, font=("Arial", 20), state="readonly")``

### 4) Adding Labels to the GUI

When creating a GUI using Tkinter, labels are used to display text. Labels can be used to identify the purpose of a button, to display the current value of a variable, or to show the result of a calculation.

To create a label in Tkinter, use the following code:

``````label = Label(canvas, text="My Label")
label.pack()``````

In the above example, `canvas` is the object that represents the canvas on which the GUI is displayed. The `text` parameter sets the text that will be displayed in the label.

You can also set other parameters to format the label. For example, to set the font of the label, use the `font` parameter:

``````label = Label(canvas, text="My Label", font=("Arial", 20))
label.pack()``````

In the above example, the font of the label is set to Arial with a size of 20.

To change the text of the label dynamically, you can use the `config` function:

``label.config(text="New Text")``

In the above example, the text of the label is changed to “New Text”. To position the label within the canvas, you can use the `place()` function:

``label.place(x=50, y=50)``

In this example, the label will be positioned at coordinates `(50, 50)` within the canvas.

## Conclusion

In this article, we discussed how to create entry boxes and labels in Tkinter when building a calculator using Python. Entry boxes provide an interface for user input, while labels allow you to display text in your GUI.

With these tools, you can create an intuitive and user-friendly calculator that is easy to use and understand. By following these steps, you can create an efficient and effective calculator that will meet your needs.

### 5) Creating the Functions and Buttons

To complete the calculator, you need to create functions for the basic operations like addition, subtraction, multiplication, and division. In this section, we will show you how to create these functions and the accompanying buttons.

### Creating the Add() function and button

The `add()` function will take two values as input, add them together, and return the result. To create the function and the button, use the following code:

``````def add():
try:
num1 = float(entry1.get())
num2 = float(entry2.get())
result = num1 + num2
output.config(text=str(result))
except ValueError:
output.config(text="Invalid Input")

In the above code, `entry1` and `entry2` are the two entry boxes in which the user inputs the values to be added.

`output` is the label where the result is displayed. If the user enters an invalid input, such as a non-numeric string, the output will display an “Invalid Input” message.

### Creating the Sub() function and button

The `sub()` function will take two values as input, subtract the second value from the first value, and return the result. To create the function and the button, use the following code:

``````def sub():
try:
num1 = float(entry1.get())
num2 = float(entry2.get())
result = num1 - num2
output.config(text=str(result))
except ValueError:
output.config(text="Invalid Input")
button_sub = Button(canvas, text="-", font=("Arial", 20), command=sub)
button_sub.place(x=80, y=150)``````

In the above code, `entry1` and `entry2` are the two entry boxes in which the user inputs the values to be subtracted.

`output` is the label where the result is displayed. The `sub()` function works similarly to the `add()` function, except it subtracts the second value from the first.

### Creating the Mul() function and button

The `mul()` function will take two values as input, multiply them together, and return the result. To create the function and the button, use the following code:

``````def mul():
try:
num1 = float(entry1.get())
num2 = float(entry2.get())
result = num1 * num2
output.config(text=str(result))
except ValueError:
output.config(text="Invalid Input")
button_mul = Button(canvas, text="*", font=("Arial", 20), command=mul)
button_mul.place(x=130, y=150)``````

In the above code, `entry1` and `entry2` are the two entry boxes in which the user inputs the values to be multiplied.

`output` is the label where the result is displayed. The `mul()` function works similarly to the `add()` and `sub()` functions, except it multiplies the two values together.

### Creating the Div() function and button

The `div()` function will take two values as input, divide the first value by the second value, and return the result. To create the function and the button, use the following code:

``````def div():
try:
num1 = float(entry1.get())
num2 = float(entry2.get())
result = num1 / num2
output.config(text=str(result))
except ZeroDivisionError:
output.config(text="Cannot Divide by Zero")
except ValueError:
output.config(text="Invalid Input")
button_div = Button(canvas, text="/", font=("Arial", 20), command=div)
button_div.place(x=180, y=150)``````

In the above code, `entry1` and `entry2` are the two entry boxes in which the user inputs the values to be divided.

`output` is the label where the result is displayed. The `div()` function works similarly to the `add()` and `sub()` functions, except it divides the first value by the second value.

If the user tries to divide by zero, the output will display a “Cannot Divide by Zero” message.

### 6) Complete Code for Building the Calculator

With all the individual components in place, let’s now bring it all together to create the complete code for building the calculator in Python using the Tkinter package:

``````from tkinter import *
root = Tk()
root.title("Calculator")
canvas = Canvas(root, width=240, height=300)
canvas.pack()
entry1 = Entry(canvas, width=15, font=("Arial", 20))
entry1.place(x=50, y=50)
entry2 = Entry(canvas, width=15, font=("Arial", 20))
entry2.place(x=50, y=100)
output = Label(canvas, text="", font=("Arial", 20))
output.place(x=115, y=200)
try:
num1 = float(entry1.get())
num2 = float(entry2.get())
result = num1 + num2
output.config(text=str(result))
except ValueError:
output.config(text="Invalid Input")
def sub():
try:
num1 = float(entry1.get())
num2 = float(entry2.get())
result = num1 - num2
output.config(text=str(result))
except ValueError:
output.config(text="Invalid Input")
def mul():
try:
num1 = float(entry1.get())
num2 = float(entry2.get())
result = num1 * num2
output.config(text=str(result))
except ValueError:
output.config(text="Invalid Input")
def div():
try:
num1 = float(entry1.get())
num2 = float(entry2.get())
result = num1 / num2
output.config(text=str(result))
except ZeroDivisionError:
output.config(text="Cannot Divide by Zero")
except ValueError:
output.config(text="Invalid Input")
button_sub = Button(canvas, text="-", font=("Arial", 20), command=sub)
button_sub.place(x=80, y=150)
button_mul = Button(canvas, text="*", font=("Arial", 20), command=mul)
button_mul.place(x=130, y=150)
button_div = Button(canvas, text="/", font=("Arial", 20), command=div)
button_div.place(x=180, y=150)
root.mainloop()``````

This code creates a simple calculator with two input fields and four buttons for the basic mathematical operations. When the user enters numbers and clicks a button, the result of the calculation is displayed in the output label.

## Conclusion

In this article, we walked you through the steps to create a simple calculator using Python and the Tkinter package. We explained how to create entry boxes for user input and labels for displaying text.

We also showed you how to create functions for the basic mathematical operations and accompanying buttons. Finally, we presented the complete code for building the calculator.

By following these steps, you should be able to create your own calculator with ease. In this article, we discussed how to build a calculator using Python and the Tkinter package.

We covered the syntax for creating the calculator, such as defining functions and GUI components, and showed how to create entry boxes and labels. We also demonstrated how to create buttons and functions for the basic mathematical operations, including addition, subtraction, multiplication, and division.

Finally, we provided the complete code for building the calculator. By following the steps outlined in this article, you can create a simple and user-friendly calculator that can be customized to meet your needs.

With Python and Tkinter, building a calculator is a great way to learn programming and enhance your skills.