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Creating a Simple Calculator using Python

Get exposed to the Python programming language by building a simple calculator app.

Beginner
Python
Workshop

Written by

@billybob

on May 26, 2024

A Step-by-Step Guide:

Python is a powerful, high-level programming language known for its simplicity and readability. It's widely used in various fields such as web development, data analysis, artificial intelligence, and more. In this guide, we'll walk you through the process of creating a simple calculator using Python. Whether you're a beginner or looking to refresh your skills, this step-by-step tutorial will help you understand Python's syntax and how to build a functional application.

What is Python?

Python is an interpreted, high-level, general-purpose programming language. Created by Guido van Rossum and first released in 1991, Python's design philosophy emphasizes code readability with its notable use of significant whitespace. Its syntax allows programmers to express concepts in fewer lines of code compared to languages such as C++ or Java.

python code

Key Features of Python:

  • Easy to read, write, and learn
  • Extensive standard library and ecosystem
  • Interpreted language (runs directly from the source code)
  • Supports multiple programming paradigms (procedural, object-oriented, functional)
  • Highly scalable and versatile

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Getting Started with Python on Replit

Replit is an online IDE that allows you to write, run, and share code directly in your browser. It supports various programming languages, including Python, making it an excellent choice for beginners.

Setting Up Replit

  1. Create an Account:

replit signup

  1. Create a New Repl:
    • After logging in, click on the "Create" button.
    • Choose "Python" from the list of languages.
    • Give your Repl a name (e.g., "Simple Calculator") and click "Create Repl".

replit dashboard

Writing Your First Python Program on Replit

Let's write a simple Python program to ensure everything is set up correctly. In your Replit environment, enter the following code in the main.py file:

print("Hello, World!")

Click the "Run" button at the top of the screen. You should see the output: Hello, World!

python hello world in replit

Python Basics

Before diving into the calculator project, let's cover some basic concepts in Python.

Variables and Data Types

Variables are used to store data. Unlike in many languages such as C++ and Java, in Python, you don't need to declare the type of a variable explicitly:

# Examples of variables number = 10 # Integer pi = 3.14 # Float name = "Alice" # String is_active = True # Boolean

Basic Arithmetic Operations

Python supports standard arithmetic operations like addition, subtraction, multiplication, and division.

a = 10 b = 5 print(a + b) # Addition: 15 print(a - b) # Subtraction: 5 print(a * b) # Multiplication: 50 print(a / b) # Division: 2.0

Functions

Functions allow you to encapsulate code into reusable blocks. You define a function using the def keyword.

def greet(name): return f"Hello, {name}!" print(greet("Alice"))

Building the Simple Calculator

Now that you have a basic understanding of Python, let's build a simple calculator. Our calculator will support addition, subtraction, multiplication, and division.

Step 1: Define the Functions

First, we need to define functions for each of the arithmetic operations.

def add(x, y): return x + y def subtract(x, y): return x - y def multiply(x, y): return x * y def divide(x, y): if y == 0: return "Error! Division by zero." else: return x / y

Step 2: Create the User Interface

Next, we'll create a simple user interface to interact with the calculator. We'll use the input() function to get user input.

def calculator(): print("Select operation:") print("1. Add") print("2. Subtract") print("3. Multiply") print("4. Divide") choice = input("Enter choice (1/2/3/4): ") if choice in ['1', '2', '3', '4']: num1 = float(input("Enter first number: ")) num2 = float(input("Enter second number: ")) if choice == '1': print(f"The result is: {add(num1, num2)}") elif choice == '2': print(f"The result is: {subtract(num1, num2)}") elif choice == '3': print(f"The result is: {multiply(num1, num2)}") elif choice == '4': print(f"The result is: {divide(num1, num2)}") else: print("Invalid input") calculator()

Step 3: Putting It All Together

Here is the complete code for the simple calculator:

def add(x, y): return x + y def subtract(x, y): return x - y def multiply(x, y): return x * y def divide(x, y): if y == 0: return "Error! Division by zero." else: return x / y def calculator(): print("Select operation:") print("1. Add") print("2. Subtract") print("3. Multiply") print("4. Divide") choice = input("Enter choice (1/2/3/4): ") if choice in ['1', '2', '3', '4']: num1 = float(input("Enter first number: ")) num2 = float(input("Enter second number: ")) if choice == '1': print(f"The result is: {add(num1, num2)}") elif choice == '2': print(f"The result is: {subtract(num1, num2)}") elif choice == '3': print(f"The result is: {multiply(num1, num2)}") elif choice == '4': print(f"The result is: {divide(num1, num2)}") else: print("Invalid input") calculator()

Conclusion

Congratulations! You've just created a simple calculator using Python. This project introduced you to Python's syntax, basic arithmetic operations, functions, and user input handling. As you continue to learn Python, you'll discover many more powerful features and libraries that can help you build more complex and exciting projects.

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Show us your final product in the Hackpost Guide discord server! Keep experimenting and happy coding!