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Python For Starters
  • Overview
  • Python for starters
  • Content
  • Foreword
  • Introduction To Python
    • Python Installation
    • Variables
    • Python Data Types
    • Python Data Structures
    • Python numbers
    • Python strings
    • Python Boolean
    • Python constants
    • Python Comments
    • Type Conversion
    • Control flow in python
  • Python Functions
    • Function Definition
    • Function Parameter
    • Recursive Functions
    • Using Global Variables in Functions
    • Lambda Functions
  • What are Data Structures
    • Python Lists
    • Python Tuples
    • Python Dictionaries
    • Python Sets
    • Iterable in python
    • Python Map, Filter & Reduce Functions
  • Error handling in Python
  • Loop ... Else Clause, Partial Functions & Type Hints
    • Partial Functions
    • Type Hints
  • Python Modules
  • Python Libraries & Packages
    • Python Packages
  • Directory & IO
    • Python IO Module
  • Pyenv
  • Virtual Environments
    • Pipenv
    • Virtualenv
  • Object Oriented Programming in Python
    • Class
    • Class Methods
    • Python Class Inheritance
    • Python Class Polymorphism
    • Python special methods
  • Appendix
  • Contributing
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On this page
  • Function with parameter
  • Working with default parameters
  • Working with arguments (*args)
  • Working with keyword arguments (**kwargs)
  1. Python Functions

Function Parameter

Function with parameter

In Python, a function parameter is a variable that is used to pass information into a function when it is called. When you define a function, you can specify the parameters that the function should accept as input. These parameters become variables that you can use within the function to perform your desired task.

# This function should return the area of a circle when given the appropriate 

# parameter Pi * r ** 2

PI = 3.142 # a constant, meaning that you should not change it [but of course can be changed eventually]

def area_of_a_circle(radius):
    result = PI * radius ** 2
    return result

area = area_of_a_circle(3)

print(area)

Working with default parameters

In Python, you can specify default values for function parameters, which will be used if the caller does not provide a value for that parameter. This can be useful if there is a common value that you want to use for a parameter in most cases, but you still want to allow the caller to override it if needed.

To specify a default value for a function parameter, you can include an assignment expression in the parameter list when defining the function

  • If a value is passed to the function when called, the value passed will override the default vale

PI = 3.142
def area_of_a_circle(radius=2):
    result = PI * radius ** 2
    return result

area = area_of_a_circle()
print(area)

Working with arguments (*args)

In Python, the *args syntax is used to pass a variable number of arguments to a function. It allows you to pass a variable number of arguments to a function as a tuple.

Here is an example of how to use *args in a function definition:

# Collecting Arguments using

def args_get_bio(*args):    
    
    print(args[0])

    print(args[1])
    
    print(args[2])

get_bio = args_get_bio(2022, "john", "solomon", 45, "Nexford")

print(get_bio)

Working with keyword arguments (**kwargs)

In Python, the **kwargs syntax is used to pass a variable-length argument dictionary to a function. It allows you to pass a variable number of keyword arguments to a function as a dictionary.

Here is an example of how to use **kwargs in a function definition:


# Collecting Arguments using **kwargs

def kwargs_get_bio(**kwargs):    
    year = kwargs['year']
    first_name = kwargs['first_name']
    print(first_name, year)
    
get_user_bio = kwargs_get_bio(first_name="John", year=2022)

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Last updated 1 year ago