examples

"""
03 - Control Flow: Examples
Run this file to see all control flow concepts in action!
"""

print("=" * 60)
print("CONTROL FLOW - EXAMPLES")
print("=" * 60)

# =============================================================================
# 1. IF-ELIF-ELSE STATEMENTS
# =============================================================================
print("\n--- 1. If-Elif-Else Statements ---\n")

# Basic if-else
age = 20
print(f"Age: {age}")
if age >= 18:
    print("You are an adult")
else:
    print("You are a minor")

# Multiple conditions with elif
print("\nGrading System:")
score = 85
print(f"Score: {score}")

if score >= 90:
    grade = "A"
elif score >= 80:
    grade = "B"
elif score >= 70:
    grade = "C"
elif score >= 60:
    grade = "D"
else:
    grade = "F"
print(f"Grade: {grade}")

# Nested if
print("\nDriving eligibility:")
age = 25
has_license = True
print(f"Age: {age}, Has License: {has_license}")

if age >= 18:
    if has_license:
        print("You can drive!")
    else:
        print("Get a license first!")
else:
    print("Too young to drive")

# =============================================================================
# 2. LOGICAL OPERATORS IN CONDITIONS
# =============================================================================
print("\n--- 2. Logical Operators ---\n")

x, y = 10, 5

# AND operator
print(f"x = {x}, y = {y}")
if x > 5 and y > 3:
    print("Both conditions are True (AND)")

# OR operator
if x > 100 or y > 3:
    print("At least one condition is True (OR)")

# NOT operator
is_raining = False
if not is_raining:
    print("It's not raining, let's go outside!")

# Complex conditions
age = 25
has_id = True
is_vip = False

if (age >= 21 and has_id) or is_vip:
    print("Access granted to VIP lounge")

# =============================================================================
# 3. TERNARY OPERATOR
# =============================================================================
print("\n--- 3. Ternary Operator ---\n")

# Simple ternary
age = 20
status = "adult" if age >= 18 else "minor"
print(f"Age {age}: {status}")

# Ternary with numbers
x = 10
result = "positive" if x > 0 else "zero or negative"
print(f"Number {x} is {result}")

# Nested ternary (use sparingly!)
score = 75
grade = "A" if score >= 90 else "B" if score >= 80 else "C" if score >= 70 else "F"
print(f"Score {score} = Grade {grade}")

# =============================================================================
# 4. TRUTHY AND FALSY VALUES
# =============================================================================
print("\n--- 4. Truthy and Falsy Values ---\n")

# Falsy values
falsy_values = [False, None, 0, 0.0, "", [], {}, (), set()]

print("Falsy values:")
for val in falsy_values:
    if not val:
        print(f"  {repr(val):15} is Falsy")

# Truthy values
truthy_values = [True, 1, -1, 0.1, "hello", [1], {"a": 1}, (1,)]

print("\nTruthy values:")
for val in truthy_values:
    if val:
        print(f"  {repr(val):15} is Truthy")

# Practical use
items = []
print(f"\nChecking list {items}:")
if items:
    print("List has items")
else:
    print("List is empty")

items = [1, 2, 3]
print(f"Checking list {items}:")
if items:
    print("List has items")
else:
    print("List is empty")

# =============================================================================
# 5. FOR LOOPS
# =============================================================================
print("\n--- 5. For Loops ---\n")

# Iterate over list
print("Iterating over list:")
fruits = ["apple", "banana", "cherry"]
for fruit in fruits:
    print(f"  {fruit}")

# Iterate over string
print("\nIterating over string 'Python':")
for char in "Python":
    print(f"  {char}", end=" ")
print()

# range() function
print("\nrange(5):", end=" ")
for i in range(5):
    print(i, end=" ")
print()

print("range(1, 6):", end=" ")
for i in range(1, 6):
    print(i, end=" ")
print()

print("range(0, 10, 2):", end=" ")
for i in range(0, 10, 2):
    print(i, end=" ")
print()

print("range(5, 0, -1):", end=" ")
for i in range(5, 0, -1):
    print(i, end=" ")
print()

# =============================================================================
# 6. ENUMERATE AND ZIP
# =============================================================================
print("\n--- 6. Enumerate and Zip ---\n")

# enumerate - get index and value
fruits = ["apple", "banana", "cherry"]
print("enumerate():")
for index, fruit in enumerate(fruits):
    print(f"  {index}: {fruit}")

print("\nenumerate(start=1):")
for index, fruit in enumerate(fruits, start=1):
    print(f"  {index}: {fruit}")

# zip - iterate multiple sequences
names = ["Alice", "Bob", "Charlie"]
ages = [25, 30, 35]
cities = ["NYC", "LA", "Chicago"]

print("\nzip() with two lists:")
for name, age in zip(names, ages):
    print(f"  {name} is {age} years old")

print("\nzip() with three lists:")
for name, age, city in zip(names, ages, cities):
    print(f"  {name}, {age}, from {city}")

# =============================================================================
# 7. WHILE LOOPS
# =============================================================================
print("\n--- 7. While Loops ---\n")

# Basic while loop
print("Count from 0 to 4:")
count = 0
while count < 5:
    print(f"  {count}")
    count += 1

# While with condition
print("\nCountdown:")
n = 5
while n > 0:
    print(f"  {n}...")
    n -= 1
print("  Liftoff! 🚀")

# While with else
print("\nWhile with else:")
count = 0
while count < 3:
    print(f"  Count: {count}")
    count += 1
else:
    print("  Loop completed normally!")

# =============================================================================
# 8. BREAK AND CONTINUE
# =============================================================================
print("\n--- 8. Break and Continue ---\n")

# break - exit loop
print("break example (find first even):")
for num in range(1, 10):
    if num % 2 == 0:
        print(f"  First even number: {num}")
        break
    print(f"  Checking {num}...")

# continue - skip iteration
print("\ncontinue example (skip evens):")
for num in range(1, 6):
    if num % 2 == 0:
        continue
    print(f"  Odd number: {num}")

# break with else
print("\nbreak with else (else won't run if break executes):")
for num in range(1, 5):
    if num == 3:
        print(f"  Found 3, breaking!")
        break
else:
    print("  Loop completed (this won't print)")

# =============================================================================
# 9. NESTED LOOPS
# =============================================================================
print("\n--- 9. Nested Loops ---\n")

# Multiplication table
print("Multiplication table (1-3):")
for i in range(1, 4):
    for j in range(1, 4):
        print(f"  {i} x {j} = {i*j}")
    print()

# Pattern printing
print("Triangle pattern:")
for i in range(1, 6):
    print("  " + "*" * i)

# =============================================================================
# 10. LIST COMPREHENSIONS
# =============================================================================
print("\n--- 10. List Comprehensions ---\n")

# Basic list comprehension
squares = [x ** 2 for x in range(5)]
print(f"Squares: {squares}")

# With condition
evens = [x for x in range(10) if x % 2 == 0]
print(f"Even numbers: {evens}")

# Transform with condition
words = ["hello", "world", "python", "hi"]
long_upper = [w.upper() for w in words if len(w) > 3]
print(f"Long words uppercase: {long_upper}")

# With if-else
numbers = [1, 2, 3, 4, 5]
labels = ["even" if n % 2 == 0 else "odd" for n in numbers]
print(f"Labels: {labels}")

# Nested list comprehension
matrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
flat = [num for row in matrix for num in row]
print(f"Flattened matrix: {flat}")

# =============================================================================
# 11. DICTIONARY AND SET COMPREHENSIONS
# =============================================================================
print("\n--- 11. Dict and Set Comprehensions ---\n")

# Dictionary comprehension
squares_dict = {x: x**2 for x in range(5)}
print(f"Squares dict: {squares_dict}")

# From two lists
names = ["a", "b", "c"]
values = [1, 2, 3]
combined = {k: v for k, v in zip(names, values)}
print(f"Combined dict: {combined}")

# Set comprehension
nums = [1, 2, 2, 3, 3, 3]
unique_squares = {x**2 for x in nums}
print(f"Unique squares set: {unique_squares}")

# =============================================================================
# 12. PRACTICAL EXAMPLES
# =============================================================================
print("\n--- 12. Practical Examples ---\n")

# Example 1: Find prime numbers
def is_prime(n):
    if n < 2:
        return False
    for i in range(2, int(n ** 0.5) + 1):
        if n % i == 0:
            return False
    return True

primes = [n for n in range(2, 30) if is_prime(n)]
print(f"Primes up to 30: {primes}")

# Example 2: FizzBuzz
print("\nFizzBuzz (1-15):")
for i in range(1, 16):
    if i % 3 == 0 and i % 5 == 0:
        print("  FizzBuzz")
    elif i % 3 == 0:
        print("  Fizz")
    elif i % 5 == 0:
        print("  Buzz")
    else:
        print(f"  {i}")

# Example 3: Menu system
print("\nMenu System (simulated):")
menu_options = {1: "Start", 2: "Options", 3: "Exit"}
for key, value in menu_options.items():
    print(f"  {key}. {value}")

# Simulating choice
choice = 2
match choice:
    case 1:
        print("  > Starting...")
    case 2:
        print("  > Opening options...")
    case 3:
        print("  > Goodbye!")
    case _:
        print("  > Invalid choice")

# Example 4: Password strength checker
def check_password_strength(password):
    strength = 0
    if len(password) >= 8:
        strength += 1
    if any(c.isupper() for c in password):
        strength += 1
    if any(c.islower() for c in password):
        strength += 1
    if any(c.isdigit() for c in password):
        strength += 1
    if any(c in "!@#$%^&*" for c in password):
        strength += 1
    return strength

passwords = ["weak", "Medium1", "Strong@123"]
print("\nPassword Strength:")
for pwd in passwords:
    score = check_password_strength(pwd)
    print(f"  '{pwd}': {score}/5 stars")

print("\n" + "=" * 60)
print("END OF EXAMPLES")
print("=" * 60)