Python functions¶

Define a function¶

The keyword def is used to define a function. Note the : after the function name, and the indentation in the function body

def greetings(name):
    print(f"Hi, {name}!")

Call a function¶

greetings(name='James bond')

Hi, James bond!

Default arguments¶

def greetings(name, language='en'):
    if language == 'pt':
        print(f"Olá, {name}!")
    else:
        print(f"Hi, {name}!")

greetings(name='James bond')

Hi, James bond!

greetings(name='James bond', language='pt')

Olá, James bond!

Note, this works as expected

greetings('James bond', 'pt')

Olá, James bond!

Also, this

greetings(language='en', name='James bond')

Hi, James bond!

and this

greetings('James bond', language='pt')

Olá, James bond!

This however, doesn’t

greetings('pt', 'James bond',)

Hi, pt!

nor this

greetings(name='James bond', 'pt')

  Input In [45]
    greetings(name='James bond', 'pt')
                                     ^
SyntaxError: positional argument follows keyword argument

Return values¶

Usually, we use function to performs some operations and return some result. For that, we use the return keyword in our function

def full_name(first_name, last_name):
    return f'{first_name} {last_name}'

name = full_name('James', 'Bond')

print(name)

James Bond

sometimes it may be convenient to pass th arguments in the form of a list (or a tuple), instead of entering each one individually.
to do that, add a * in front of the list (tuple), like this

name_parts = ['James', 'Bond']

full_name(*name_parts)

'James Bond'

Built-in functions¶

Python comes with some built-in functions. We have seen several of them, such as print, type, enumerate. A full list of the existing built in functions can be seen here

Python functions

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