Day 2 – Control Flow & Data Handling

# Simple if statement
age = 18

if age >= 18:
    print("You are an adult!")
    print("You can vote!")

print("Program continues...")

# if-else statement
temperature = 25

if temperature > 30:
    print("It's hot outside!")
else:
    print("It's not too hot.")

# if-elif-else statement
score = 85

if score >= 90:
    grade = "A"
    print("Excellent!")
elif score >= 80:
    grade = "B"
    print("Good job!")
elif score >= 70:
    grade = "C"
    print("Not bad!")
else:
    grade = "F"
    print("Need improvement!")

print(f"Your grade is: {grade}")

# Nested conditionals
age = 20
has_license = True

if age >= 18:
    if has_license:
        print("You can drive!")
    else:
        print("You need a license to drive.")
else:
    print("You are too young to drive.")

# Basic for loop
print("Counting from 1 to 5:")
for i in range(1, 6):
    print(i)

# Range with step
print("\nEven numbers from 2 to 10:")
for i in range(2, 11, 2):
    print(i)

# Countdown
print("\nCountdown:")
for i in range(5, 0, -1):
    print(i)
print("Blast off!")

# Iterating through a string
word = "Python"

print("Letters in 'Python':")
for letter in word:
    print(letter)

# Iterating through a list
fruits = ["apple", "banana", "cherry"]
print("\nFruits:")
for fruit in fruits:
    print(f"I like {fruit}!")

# Basic while loop
count = 1

while count <= 5:
    print(f"Count: {count}")
    count = count + 1  # or count += 1

print("Loop finished!")

# Using break
print("Finding first even number:")
for num in range(1, 10):
    if num % 2 == 0:
        print(f"Found: {num}")
        break  # Exit loop immediately

# Using continue
print("\nPrinting odd numbers:")
for num in range(1, 10):
    if num % 2 == 0:
        continue  # Skip to next iteration
    print(num)

# Creating lists
fruits = ["apple", "banana", "cherry"]
numbers = [1, 2, 3, 4, 5]
mixed = [1, "hello", 3.14, True]

print("Fruits:", fruits)
print("Numbers:", numbers)
print("Mixed:", mixed)

# Accessing elements
print("\nFirst fruit:", fruits[0])
print("Last fruit:", fruits[-1])

# Modifying lists
fruits.append("orange")  # Add to end
print("\nAfter adding orange:", fruits)

fruits.insert(1, "grape")  # Insert at position
print("After inserting grape:", fruits)

fruits.remove("banana")  # Remove item
print("After removing banana:", fruits)

# List slicing
print("\nFirst two fruits:", fruits[0:2])
print("All fruits:", fruits[:])

# Creating tuples
coordinates = (10, 20)
colors = ("red", "green", "blue")

print("Coordinates:", coordinates)
print("Colors:", colors)

# Accessing elements
print("\nX coordinate:", coordinates[0])
print("Y coordinate:", coordinates[1])

# Tuples are immutable - this would cause an error:
# coordinates[0] = 15  # TypeError!

# Unpacking tuples
x, y = coordinates
print(f"\nUnpacked: x = {x}, y = {y}")

# Creating dictionaries
student = {
    "name": "Alice",
    "age": 20,
    "grade": "A"
}

print("Student:", student)

# Accessing values
print("\nName:", student["name"])
print("Age:", student.get("age"))

# Adding/updating values
student["email"] = "[email protected]"
student["age"] = 21
print("\nUpdated student:", student)

# Removing items
del student["grade"]
print("After removing grade:", student)

# Dictionary methods
print("\nKeys:", student.keys())
print("Values:", student.values())
print("Items:", student.items())

# Define a function
def greet():
    print("Hello, World!")
    print("Welcome to Python!")

# Call the function
greet()
greet()  # Can call multiple times

# Function with parameters
def greet_person(name):
    print(f"Hello, {name}!")
    print("Nice to meet you!")

# Call with different arguments
greet_person("Alice")
greet_person("Bob")

# Function with multiple parameters
def introduce(name, age):
    print(f"My name is {name} and I am {age} years old.")

introduce("Charlie", 25)

# Function that returns a value
def add_numbers(a, b):
    result = a + b
    return result

# Use the return value
sum_result = add_numbers(5, 3)
print("Sum:", sum_result)

# Another example
def calculate_area(length, width):
    area = length * width
    return area

room_area = calculate_area(10, 8)
print(f"Room area: {room_area} square feet")

# Function to check if number is even
def is_even(number):
    if number % 2 == 0:
        return True
    else:
        return False

print("Is 4 even?", is_even(4))
print("Is 7 even?", is_even(7))

# Function to find maximum of two numbers
def find_max(a, b):
    if a > b:
        return a
    else:
        return b

max_num = find_max(10, 20)
print(f"Maximum: {max_num}")

# Function to calculate average
def calculate_average(numbers):
    total = sum(numbers)
    count = len(numbers)
    return total / count

scores = [85, 90, 78, 92, 88]
avg = calculate_average(scores)
print(f"Average score: {avg}")