Python Functions Tutorial

Functions in Python are defined using the def keyword, and they allow you to organize your code into reusable blocks. Functions can accept parameters, perform a set of actions, and return a value. Here’s a detailed look at functions in Python with various examples to illustrate how to define, call, and use functions for different purposes.

Basic Function Definition and Calling


Passing Parameters

Functions can take parameters, allowing you to pass data into the function.


Returning Values

Use the return statement to send back a value from a function to the caller.


Default Parameter Values

You can assign default values to parameters. These defaults are used if no argument is passed during the function call.


Keyword Arguments

When calling functions, you can use keyword arguments to specify which parameter gets which argument, allowing for more clarity and flexibility.


Arbitrary Number of Arguments

Sometimes you might not know how many arguments will be passed into your function. Python allows you to handle this with *args for positional arguments and **kwargs for keyword arguments.

Example with *args:

Example with **kwargs:

Function Annotations

Python 3.5+ introduces function annotations, which are a way of associating expressions with various parts of functions. These expressions are not enforced at runtime but can be used by third-party tools and documentation.


Nested Functions

You can define functions inside other functions. These are often used for organization or when a function is only needed within another function’s scope.


Lambda Functions

Lambda functions are small anonymous functions defined with the lambda keyword. They can have any number of arguments but only one expression.


Functions in Python are a powerful way to abstract and reuse code, making your programs more modular, readable, and maintainable. By understanding how to define and use functions, you can significantly enhance your Python programming capabilities.

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