Functions with Outputs

first_name = input("Enter your first name: ")
last_name = input("Enter your last name: ")
def format_name(f_name, l_name):
    """Take a first and last name and format it to return the title case version of the name."""
    #Early return to end the function
    if f_name == "" or l_name == "":
        return "You didnt input valid inputs."
    fromated_f_name = f_name.title()
    fromated_l_name = l_name.title()

    return f"{fromated_f_name} {fromated_l_name}"

formated_string = format_name(first_name, last_name)
print(formated_string)

• Multiple Return Values: We can use more than one return in one function
• Empty return function

def function()
    return 

value= function()
print(value)

#output
None

Docstrings

It is a way of documenting a functions.

def format_name(f_name, l_name):
    #Docstring
    """Take a first and last name and format it to return the title case version of the name."""
    #Early return to end the function
    if f_name == "" or l_name == "":
        return "You didnt input valid inputs."
    fromated_f_name = f_name.title()
    fromated_l_name = l_name.title()
    return f"{fromated_f_name} {fromated_l_name}"

format_name()

When ever we will call our function, it will show definition of that function that we wrote as a Docstring. You can see in the image below.

It can also be use for Multilines String and Multiline Comments.

Print vs Return

Printing and returning are completely different concepts.

print is a function you call. Calling print will immediately make your program write out text for you to see. Use print when you want to show a value to a human.

return is a keyword. When a return statement is reached, Python will stop the execution of the current function, sending a value out to where the function was called. Use return when you want to send a value from one point in your code to another.

Using return changes the flow of the program. Using print does not.

Source: pythonprinciples

Recursion

When a function call it self, it is called recursion.

Note⚠️: Function must call it self under certain condition otherwise it won't stop calling it self and its execution never ends.

a=2
def function(a)
    if a=2:
        function(a)
function(a)

Project

Built a simple calculator see the code on Github