If you have done or read some coding you would have come across *args and **kwargs . They are used while defining functions and its arguments.

def display_info(*args, **kwargs):
	# code
	pass

What are those? Let’s find out.

Usage of *args

*args allows you to pass a variable number of positional arguments to a function. The arguments are collected into a tuple, which can be iterated over or used as needed.

  • Use *args when you don’t know how many positional arguments will be passed to the function.
  • If no arguments are passed, *args will simply be an empty tuple.
  • When using *args with regular parameters, the regular parameters must appear before *args.
  • Use *args when you need to iterate through the arguments.

Example

def greet(greeting, *names):
    for name in names:
        print(f'{greeting}, {name}!')

greet('Hi', "Alice", "Bob", 'Charlie')

# Output
Hi, Alice!
Hi, Bob!
Hi, Charlie!
  • Note that the greeting parameter is defined before *names.
  • The variable *args can be replaced with any name; the only rule is to use an asterisk (*) before the variable name.

Usage of **kwargs

**kwargs allows a function to accept a variable number of keyword arguments. These arguments are collected into a dictionary, where the keys are the argument names (strings) and the values are the corresponding values.

  • Use **kwargs when you don’t know how many keyword arguments will be passed to the function.
  • If no arguments are passed, **kwargs will simply be an empty dictionary.
  • When using **kwargs with regular parameters, the regular parameters must appear before **kwargs.
  • If you are using both *args and **kwargs in a function, *args must come before **kwargs in the parameters list.
  • Use **kwargs when the function should accept optional configuration parameters.

Example

def introduce(greeting, **kwargs):
    print(greeting)
    for key, value in kwargs.items():
        print(f"{key}: {value}")

introduce("Hello!", name="Alice", hobby="Painting")

# Output
Hello! 
name: Alice 
hobby: Painting
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