# Creating variables
name = "Alex"
age = 35
hourly_rate = 45.50
is_python_fun = True

# Integers (whole numbers)
count = 10
negative_number = -5

# Floating-point (decimals)
pi = 3.14159
discount_rate = 0.15

# Complex numbers
complex_number = 3 + 4j  # Not often used in business applications

# Text enclosed in quotes (single or double)
first_name = "John"
last_name = 'Doe'

# Multi-line strings use triple quotes
address = """123 Main Street
Anytown, CA 12345"""

# String concatenation
full_name = first_name + " " + last_name  # "John Doe"

# f-strings (Python 3.6+) - my preferred way to format strings
greeting = f"Hello, {first_name}! You are {age} years old."

# True or False values
is_active = True
has_paid = False

# Boolean operations
is_valid_customer = is_active and has_paid  # False
can_contact = is_active or has_paid  # True
is_not_active = not is_active  # False

# Represents absence of value (similar to NULL in databases)
result = None

# String to number
age_str = "35"
age_num = int(age_str)  # 35 as integer
price_float = float("45.50")  # 45.5 as float

# Number to string
count_str = str(10)  # "10" as string

# Check type of a variable
print(type(age_num))  # <class 'int'>

a = 10
b = 3

addition = a + b        # 13
subtraction = a - b     # 7
multiplication = a * b  # 30
division = a / b        # 3.3333... (always returns float)
floor_division = a // b # 3 (integer division, rounds down)
modulus = a % b         # 1 (remainder of division)
exponent = a ** b       # 1000 (10 raised to power of 3)

a = 10
b = 3

equal = a == b              # False
not_equal = a != b          # True
greater_than = a > b        # True
less_than = a < b           # False
greater_or_equal = a >= b   # True
less_or_equal = a <= b      # False

# Simple assignment
x = 10

# Combined operators
x += 5   # Same as x = x + 5 (x becomes 15)
x -= 3   # Same as x = x - 3 (x becomes 12)
x *= 2   # Same as x = x * 2 (x becomes 24)
x /= 4   # Same as x = x / 4 (x becomes 6.0)

age = 25

if age < 18:
    print("Minor")
elif age < 65:
    print("Adult")
else:
    print("Senior")

income = 75000
years_employed = 3

if income > 50000 and years_employed >= 2:
    print("Loan approved")
elif income > 30000 or years_employed >= 5:
    print("Further review needed")
else:
    print("Loan denied")

# Loop through a list
expenses = [1200, 450, 700, 95]
total = 0
for expense in expenses:
    total += expense

print(f"Total expenses: ${total}")  # Total expenses: $2445

# Loop with a range
for i in range(5):  # 0, 1, 2, 3, 4
    print(i)

# Loop with index and value using enumerate
for index, value in enumerate(expenses):
    print(f"Expense {index+1}: ${value}")

count = 0
while count < 5:
    print(count)
    count += 1  # Don't forget this or you'll create an infinite loop!

# Break and continue
number = 0
while True:  # Infinite loop
    number += 1
    if number == 3:
        continue  # Skip the rest of this iteration
    if number == 6:
        break  # Exit the loop entirely
    print(number)  # Prints 1, 2, 4, 5

# Traditional way
numbers = [1, 2, 3, 4, 5]
squares = []
for n in numbers:
    squares.append(n * n)
print(squares)  # [1, 4, 9, 16, 25]

# With list comprehension
squares = [n * n for n in numbers]
print(squares)  # [1, 4, 9, 16, 25]

# With conditional filtering
even_squares = [n * n for n in numbers if n % 2 == 0]
print(even_squares)  # [4, 16]

# Dictionary comprehension
number_to_square = {n: n * n for n in numbers}
print(number_to_square)  # {1: 1, 2: 4, 3: 9, 4: 16, 5: 25}

# Set comprehension (eliminates duplicates)
values = [1, 2, 2, 3, 4, 4, 5]
unique_values = {v for v in values}
print(unique_values)  # {1, 2, 3, 4, 5}

# Traditional function
def add(a, b):
    return a + b

# Equivalent lambda function
add_lambda = lambda a, b: a + b

print(add(2, 3))        # 5
print(add_lambda(2, 3)) # 5

# Map applies a function to each item in an iterable
numbers = [1, 2, 3, 4, 5]
squared = list(map(lambda x: x * x, numbers))
print(squared)  # [1, 4, 9, 16, 25]

# Filter creates a list of elements for which a function returns True
even_numbers = list(filter(lambda x: x % 2 == 0, numbers))
print(even_numbers)  # [2, 4]

# Sorted with a custom key function
employees = [
    {"name": "Alice", "salary": 60000},
    {"name": "Bob", "salary": 50000},
    {"name": "Charlie", "salary": 75000}
]
sorted_by_salary = sorted(employees, key=lambda emp: emp["salary"])
print(sorted_by_salary)  # Sorts employees by salary

# Lists, tuples, dictionaries, and sets are all iterable
numbers = [1, 2, 3]
for num in numbers:  # numbers.__iter__() is called implicitly
    print(num)

# Manual iteration with iter() and next()
numbers = [1, 2, 3]
iterator = iter(numbers)

print(next(iterator))  # 1
print(next(iterator))  # 2
print(next(iterator))  # 3
# print(next(iterator))  # Would raise StopIteration exception

def count_up_to(max):
    count = 1
    while count <= max:
        yield count
        count += 1

# Using the generator
counter = count_up_to(5)
print(next(counter))  # 1
print(next(counter))  # 2

# Or in a loop
for number in count_up_to(3):
    print(number)  # Prints 1, 2, 3

# Basic try/except
try:
    result = 10 / 0  # Division by zero raises an exception
    print(result)
except ZeroDivisionError:
    print("Cannot divide by zero!")

# Handling multiple exception types
try:
    number = int(input("Enter a number: "))
    result = 100 / number
    print(result)
except ValueError:
    print("That's not a valid number!")
except ZeroDivisionError:
    print("Cannot divide by zero!")

# Try/except/else/finally
try:
    file = open("data.txt", "r")
    content = file.read()
except FileNotFoundError:
    print("File not found!")
else:
    # Runs if no exception occurred
    print(f"File content: {content}")
finally:
    # Always runs, regardless of exception
    if 'file' in locals() and not file.closed:
        file.close()
        print("File closed!")

def calculate_savings_projection(monthly_savings, annual_interest_rate, years):
    # Convert annual interest rate to monthly and decimal
    monthly_rate = annual_interest_rate / 100 / 12
    months = years * 12
    
    # Project savings
    total = 0
    for month in range(1, months + 1):
        total = total + monthly_savings  # Add monthly contribution
        interest = total * monthly_rate  # Calculate interest
        total = total + interest         # Add interest to total
        
        # Print yearly totals
        if month % 12 == 0:
            print(f"Year {month // 12}: ${total:.2f}")
    
    return total

try:
    income = float(input("Enter your monthly income: $"))
    expenses = float(input("Enter your monthly expenses: $"))
    
    monthly_savings = income - expenses
    if monthly_savings <= 0:
        print("Your expenses exceed your income. No savings to project.")
    else:
        interest_rate = float(input("Enter annual interest rate (%): "))
        years = int(input("Enter number of years to project: "))
        
        print(f"\nMonthly savings: ${monthly_savings:.2f}")
        print(f"Projecting growth over {years} years at {interest_rate}% annual interest:")
        
        final_amount = calculate_savings_projection(monthly_savings, interest_rate, years)
        print(f"\nFinal savings after {years} years: ${final_amount:.2f}")
        
except ValueError:
    print("Please enter valid numbers only.")