How do I define a function with optional arguments?

11    Asked by FreemanPacifico in Python , Asked on May 20, 2025

 Want to make your Python functions more flexible? Learn how to define functions with optional parameters using default values or *args and **kwargs to handle varying numbers of arguments smoothly.

Answered by Miguel Angel

Defining a function with optional arguments in Python is a great way to make your code more flexible and user-friendly. Optional arguments allow you to call the function with fewer parameters if needed, without breaking the code.

Here's how you can define a function with optional arguments:

Using default parameter values

 You can assign a default value to a parameter in the function definition. If the caller does not provide that argument, Python will use the default.

def greet(name, greeting="Hello"):
    print(f"{greeting}, {name}!")

  • greet("Alice") will print "Hello, Alice!"
  • greet("Bob", "Hi") will print "Hi, Bob!"

Using *args for variable-length positional arguments

 Useful when you're not sure how many arguments might be passed.

def add_numbers(*numbers):
    return sum(numbers)

Using **kwargs for variable-length keyword arguments

 Lets you pass any number of named arguments.

def print_info(**info):
    for key, value in info.items():
        print(f"{key}: {value}")

Key Tips:

  • Always place required arguments first, followed by optional ones.
  • Default values can be strings, numbers, or even None.
  • Using *args and **kwargs gives you the most flexibility, especially in dynamic situations.



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