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38. Function Arguments and Return Values

1. Introduction​

Functions take inputs (arguments) and may produce outputs (return values). Understanding how arguments are passed and how returns work is essential.

2. Positional Arguments​

def multiply(a, b):
    return a * b

print(multiply(2, 3))  # 6

3. Keyword Arguments (Named Arguments)​

def greet(name, age):
    print(f"Hello {name}, you are {age} years old")

greet(age=30, name="Alice")

4. Default Return Value (None)​

If a function does not return explicitly, it returns None.

def say_hi():
    print("Hi")

result = say_hi()
print(result)  # None

5. Returning Multiple Values​

Functions can return tuples which can be unpacked.

def stats(numbers):
    return min(numbers), max(numbers), sum(numbers)

low, high, total = stats([1, 2, 3])
print(low, high, total)

6. Arguments vs Parameters​

  • Parameters are names in function definition.
  • Arguments are actual values passed to the function.

7. Type Hints (Optional)​

Python supports optional type hints for better readability and tooling:

def add(a: int, b: int) -> int:
    return a + b

8. Best Practices​

  • Validate arguments where appropriate.
  • Return early if inputs are invalid.
  • Keep return types consistent for easier use.

9. Next Steps​

✅ You now understand arguments and return values.
Next: Default and keyword arguments.