functions in python

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 whenever necessary.

Quick intro to functions in python

Creating a function

• 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:

Calling a function

• 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 ;)

Passing arguments to a function

• 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.

There you go, now you can create your own functions and play with it.

Code along and fun.