➕ Lesson 59: Add Two Numbers (Basic Arithmetic & User Input)
1. Problem Overview
In short → In Python, we want the user to enter two numbers, add them together, and show the result.
In other words → The task is to take two numbers as input from the user, add them, and display the result.
2. Methods
- Static numbers → direct assignment
- User input →
input()function - Function-based → reusable code
- Lambda function → one-line solution
3. Summary
✅ Basic arithmetic → addition operator (+)
✅ User input → input() + int() conversion
✅ Function-based → reusable, clean code
✅ Error handling → validate numeric input
python
# ===== 1. Using Static Numbers =====
a = 5
b = 7
result = a + b
print(f"{a} + {b} = {result}")
# ===== 2. Using User Input =====
print(f"\n===== User Input =====")
# In real app: a = int(input("Enter first number: "))
# In real app: b = int(input("Enter second number: "))
# Demo with fixed values:
a = 10
b = 20
result = a + b
print(f"Enter first number: {a}")
print(f"Enter second number: {b}")
print(f"The sum is: {result}")
# ===== 3. Using Function =====
print(f"\n===== Using Function =====")
def add_numbers(x, y):
return x + y
num1 = 15
num2 = 25
print(f"The sum is: {add_numbers(num1, num2)}")
# ===== 4. Using Lambda Function =====
print(f"\n===== Using Lambda =====")
add = lambda x, y: x + y
print(f"Lambda: {add(30, 40)}")
# ===== 5. Error Handling =====
print(f"\n===== Error Handling =====")
def safe_add():
try:
# In real app: a = int(input("Enter first number: "))
# In real app: b = int(input("Enter second number: "))
a, b = 50, 60
result = a + b
return f"The sum is: {result}"
except ValueError:
return "Error: Please enter valid numbers!"
print(safe_add())You should see
5 + 7 = 12 ===== User Input ===== Enter first number: 10 Enter second number: 20 The sum is: 30 ===== Using Function ===== The sum is: 40 ===== Using Lambda ===== Lambda: 70 ===== Error Handling ===== The sum is: 110