Day 7: Build a Calculator - One Week Python

🎉

Congratulations!

You've made it to the final day! Today you'll build a complete calculator using everything you've learned.

📋 Project Overview

Your calculator should:

Take two numbers as input
Ask which operation (+, -, *, /)
Perform the calculation
Handle errors (like division by zero)
Let the user do multiple calculations

💻 The Calculator Code

def add(a, b):
    return a + b

def subtract(a, b):
    return a - b

def multiply(a, b):
    return a * b

def divide(a, b):
    if b == 0:
        return "Error: Cannot divide by zero!"
    return a / b

def calculator():
    print("🧮 Simple Calculator")
    print("Operations: +, -, *, /")
    print("Type 'quit' to exit\n")
    
    while True:
        operation = input("Operation: ")
        
        if operation == "quit":
            print("Goodbye! 👋")
            break
        
        try:
            num1 = float(input("First number: "))
            num2 = float(input("Second number: "))
        except ValueError:
            print("❌ Please enter valid numbers!\n")
            continue
        
        if operation == "+":
            print(f"Result: {add(num1, num2)}\n")
        elif operation == "-":
            print(f"Result: {subtract(num1, num2)}\n")
        elif operation == "*":
            print(f"Result: {multiply(num1, num2)}\n")
        elif operation == "/":
            print(f"Result: {divide(num1, num2)}\n")
        else:
            print("❌ Invalid operation! Use +, -, *, or /\n")

# Run the calculator
calculator()
            

📖 How It Works

Functions - We created separate functions for each operation
While Loop - Keeps the calculator running until user quits
Try/Except - Handles invalid number inputs gracefully
If/Elif/Else - Chooses which operation to perform
F-strings - Formats the output nicely

💡 Try This: Add more operations like power (**), modulo (%), or floor division (//). Can you add a history feature that remembers past calculations?

🚀 Challenge Extensions

Want to make it even better? Try these:

History: Store all calculations in a list and show them on exit
GUI: Use Python's tkinter library for a graphical calculator
Scientific: Add sqrt, sin, cos using the math module
Save/Load: Save calculation history to a file

🧮 Day 7: Build a Calculator

Congratulations!

📋 Project Overview

💻 The Calculator Code

📖 How It Works

🚀 Challenge Extensions

You Did It!

What You Learned: