functions_scope.py

# Python Functions and Scope
# ------------------------------

# 1. DEFINING FUNCTIONS
# A way to wrap code into a reusable block.
def greet(name):
    """This function greets the person passed in as a parameter."""
    return f"Hello, {name}!"

# Calling the function
message = greet("Alice")
print(message)


# 2. DEFAULT ARGUMENTS
# You can provide default values for parameters.
def power(base, exponent=2):
    return base ** exponent

print(f"\n2 squared: {power(2)}")      # Uses default 2
print(f"2 cubed: {power(2, 3)}")      # Overrides default with 3


# 3. GLOBAL VS. LOCAL SCOPE
# Variables created inside a function stay inside (Local).
# Variables created outside are accessible everywhere (Global).
count = 10 # Global variable

def increment():
    # To modify a global variable, you must use the 'global' keyword
    global count
    count += 1
    local_val = 5 # Local variable
    print(f"Inside function: count={count}, local_val={local_val}")

increment()
# print(local_val) # This would crash because local_val only exists inside increment()


# ------------------------------
# EXERCISE TODO:
# 1. Write a function 'calculate_area' that takes 'width' and 'height'. 
#    It should return width * height.
# 2. Create a function 'describe_pet' with parameters 'name' and 'animal_type'.
#    Set the default 'animal_type' to "dog".
# 3. Create a global variable 'total' = 0. Write a function 'add_to_total(amount)' 
#    that adds the amount to the global 'total' variable.