Building a Simple Calculator in Python: A Step-by-Step Guide

Python, known for its simplicity and versatility, is an excellent language for creating a wide range of applications, including calculators. In this article, we’ll walk through the process of building a basic calculator in Python. We’ll cover fundamental programming concepts such as user input, arithmetic operations, and conditional statements.

1. Designing the Calculator:

Before diving into the code, let’s outline the basic functionalities we want our calculator to have. For simplicity, we’ll focus on the four basic arithmetic operations: addition, subtraction, multiplication, and division.

2. Getting User Input:

To start, we need to get input from the user. We’ll use the input() function to prompt the user for the numbers and the operation they want to perform.

def get_user_input():
    num1 = float(input("Enter the first number: "))
    operator = input("Enter the operator (+, -, *, /): ")
    num2 = float(input("Enter the second number: "))
    return num1, operator, num2

3. Performing Arithmetic Operations:

Next, we’ll create functions for each arithmetic operation. These functions will take two numbers as input and return the result of the corresponding operation.

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 x / y
        return "Cannot divide by zero"

4. Calculating the Result:

Now, we’ll use the user input and the corresponding arithmetic function to calculate the result.

def calculate_result(num1, operator, num2):
    if operator == '+':
        return add(num1, num2)
    elif operator == '-':
        return subtract(num1, num2)
    elif operator == '*':
        return multiply(num1, num2)
    elif operator == '/':
        return divide(num1, num2)
        return "Invalid operator"

5. Displaying the Result:

Finally, we’ll create a function to display the result to the user.

def display_result(result):
    print("Result:", result)

6. Putting it All Together:

Now, let’s combine the functions to create our calculator.

def main():
        num1, operator, num2 = get_user_input()
        result = calculate_result(num1, operator, num2)
    except ValueError:
        print("Invalid input. Please enter valid numbers.")
    except Exception as e:
        print(f"An error occurred: {e}")

if __name__ == "__main__":

7. Testing the Calculator:

Let’s test our calculator by running the script. Enter two numbers and the desired operator, and the calculator will display the result.

Enter the first number: 10
Enter the operator (+, -, *, /): *
Enter the second number: 5
Result: 50.0


Building a simple calculator in Python is a great way to practice fundamental programming concepts. This project covers user input, basic arithmetic operations, error handling, and modular programming.

Feel free to expand the functionality of the calculator by adding more operations, implementing a graphical user interface (GUI), or incorporating additional features. This project serves as a solid foundation for further exploration and development in Python programming. Happy coding!

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