Python Functions Tutorial for Absolute Beginners

Alright, let's start with what functions actually are?

• OK, a function is a piece of code.
• A function may/may not accept input(s).
• A function may/may not return an output(s).

Why do we need functions in a program?

• Well, the Reusability of the code in a program is made possible through functions.
• The program can call these so-called functions, n - number of times.
• This showcases the best practice in a program called DRY.

DRY - Do not Repeat Yourself

• A code is said to be DRY if any given code does not repeat certain tasks.
• A function implements this just by writing once and using it whenever necessary.

A quick intro to functions in python

• To create a function we use the keyword 

  def

  .

• def

   must be followed by the function name.
• followed by a parenthesis filled with formal parameters(optional).
• The statements that follow up makes the body of the function.
• Note: Any code written inside a function must be indented.
• Let's see an example where I thank every one of my readers:

• To call a function we use the function name followed by parenthesis filled with actual parameter also known as arguments.
• This is when the code inside the function actually gets executed.
• Let's see the same example and its output:

• Output:

Hello there John Doe
Thank you for taking your time to read my post ;)
Hello there Jane Doe
Thank you for taking your time to read my post ;)

• We can pass arguments to a function through the function call.
• We do this by writing the arguments inside the parenthesis of a function call.
• Didn't you notice passing arguments to a function already? Look into the above example closely:

reader("John Doe")
reader("Jane Doe")

• The function call 

  reader()

   passes the strings "John Doe" and "Jane Doe" as arguments to the function.