Calculator App (Enhanced)

🐍 Lesson 42: Calculator App (Python Project)

1. Project Overview

In short → A calculator app is one of the easiest projects for Python beginners, handling basic addition, subtraction, multiplication, division arithmetic operations.

In detail → A calculator app is a beginner-friendly project that performs basic arithmetic operations like addition, subtraction, multiplication, and division.

2. Why Build a Calculator App?

You get to practice Python functions, loops, and conditionals
You learn how to handle user input
You get to try out error handling (for example, division by zero)

3. Summary

✅ Calculator app = beginner-friendly project

✅ CLI version → practice with functions, loops, conditionals

✅ GUI version → an interactive app built with Tkinter

✅ Error handling → division by zero, invalid input

python

# ===== 1. Basic Calculator Functions =====
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! Division by zero."
    return a / b

# ===== 2. Calculator Loop =====
print("===== Simple Calculator =====")
print("Operations: +, -, *, /")
print("Enter 'q' to quit\n")

while True:
    choice = input("Enter operation (+, -, *, /) or 'q' to quit: ")
    if choice == 'q':
        break
    
    try:
        num1 = float(input("Enter first number: "))
        num2 = float(input("Enter second number: "))
        
        if choice == '+':
            print(f"Result: {add(num1, num2)}\n")
        elif choice == '-':
            print(f"Result: {subtract(num1, num2)}\n")
        elif choice == '*':
            print(f"Result: {multiply(num1, num2)}\n")
        elif choice == '/':
            result = divide(num1, num2)
            print(f"Result: {result}\n")
        else:
            print("Invalid operation\n")
    except ValueError:
        print("Invalid input! Please enter numbers.\n")

# ===== 3. Example Usage =====
print(f"\n===== Example Calculations =====")
print(f"5 + 3 = {add(5, 3)}")
print(f"10 - 4 = {subtract(10, 4)}")
print(f"6 * 7 = {multiply(6, 7)}")
print(f"15 / 3 = {divide(15, 3)}")
print(f"10 / 0 = {divide(10, 0)}")

You should see

===== Simple Calculator ===== Operations: +, -, *, / Enter 'q' to quit ===== Example Calculations ===== 5 + 3 = 8 10 - 4 = 6 6 * 7 = 42 15 / 3 = 5.0 10 / 0 = Error! Division by zero.