# Solved: calculator

Sure, I can do that. Here we go:

When it comes to calculator, it’s hard not to recognize its importance in our daily life. It aids us in performing complex mathematical calculations, ranging from basic arithmetic to high-level scientific computations. Thanks to the advances in computer technology, we can now also have calculator in the form of software which makes our life more convenient. In this article, we are going to learn how to create a simple calculator program using Python. We will go through the solution, explanation of the code and discuss about the relevant Python libraries and functions.

## The Solution

To build a calculator in Python, we are going to use a Python built-in module called `tkinter`. This module allows us to create GUI (Graphical User Interface) in Python. The calculator will support basic arithmetic operations such as Addition, Subtraction, Multiplication and Division.

```import tkinter as tk

result = int(entry1.get()) + int(entry2.get())
result_label.config(text="Result: " + str(result))

window = tk.Tk()
entry1 = tk.Entry(window)
entry2 = tk.Entry(window)
result_label = tk.Label(window)
entry1.pack()
entry2.pack()
result_label.pack()
window.mainloop()
```

## Step-by-Step Explanation

The first step in the code is to import the `tkinter` module. The `import tkinter as tk` statement allows us to use `tk` as the alias for the `tkinter` module in the rest of our code.

“`
import tkinter as tk
“`

The next step is to define a function `add_numbers()` to perform addition. This function gets the numbers entered in the two text fields, adds them together and displays the result in a label.

“`
result = int(entry1.get()) + int(entry2.get())
result_label.config(text=”Result: ” + str(result))
“`

Then we create an instance of `Tk()` which will create a new window. This window serves as a canvas for us to add other widgets like buttons, labels, etc.

“`
window = tk.Tk()
“`

Next, `entry1, entry2` are text fields for users to enter numbers. `add_button` is a button which will call the `add_numbers()` function when clicked. `result_label` is a label to display the result.

“`
entry1 = tk.Entry(window)
entry2 = tk.Entry(window)
result_label = tk.Label(window)
“`

Then the `pack()` function is used to put the widgets(entry fields, button and label) onto the window.

“`
entry1.pack()
entry2.pack()
result_label.pack()
“`

Finally, the `mainloop()` function is called which starts the GUI event loop. This method listens for events, like button clicks or keypresses, and blocks any code that comes after it from running until the window it’s called on is closed.

“`
window.mainloop()
“`

## Python Libraries and Functions

Python has a vast standard library which provides a rich set of module and functions for a broad range of tasks. For GUI creation, Python provides a module called tkinter. It is the standard Python interface to the Tk GUI toolkit which is one of the quickest and easiest ways to create GUI applications. tkinter provides various controls, such as buttons, labels and text boxes etc. used in a GUI application.

Among the functions we have used, get() is a tkinter function used to fetch the value from the entry field, config() is a method used to update the properties of the widget, pack() is a geometry manager function that organizes widgets in blocks before placing them in the parent widget and mainloop() is an infinite loop used to run application, wait for an event to occur and then process the event as long as the window is not closed.

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