Python Function with Examples

In this article, you’ll see how to use a function in Python. The function is a set of code that we define once and can reuse many times.

How to create a function in Python

The def keyword is used to define a function in Python. In the following example, my_fun() is the name of the function.

# define a function
def my_fun():
    print("AiHints")

# call the function
my_fun()

Output:

AiHints

Python Function arguments

You can use arguments to pass information in a function.

# define a function
def my_fun(name):
    print("Hello", name)

# call the function
my_fun("Hussain")
my_fun("John")
my_fun("Smith")

Output:

Hello Hussain
Hello John
Hello Smith

Multiple Arguments

You can also define a function with multiple arguments.

# define a function
def my_fun(a, b):
    print(a + b)
    print(a - b)
    print(a * b)
    print(a / b)

# call the function
my_fun(20, 10)

Output:

30
10
200
2.0

Number of arguments is unknown

When the number of arguments is unknown, you can use * in the parenthesis before the argument.

# define a function
def my_fun(*names):
    print("Hello", names[2])

# call the function
my_fun("Hussain", "John", "Smith", "Satish")

Output:

Hello Smith

Another Example

# define a function
def my_fun(**Skills):
    print("His Skills are", Skills["first"], "and", Skills["second"])

# call the function
my_fun(first = "Python", second = "R", third = "SQL")

Output:

His Skills are Python and R

Order of the arguments

The following example will give you an idea that in some cases the order of the arguments does not matter.

# define a function
def my_fun(c, a, b):
    print("The value of a is", a)

# call the function
my_fun(b = 10, c = 20, a = 30)

Output:

The value of a is 30

List in Function

You can also use a list in the function. The following two examples will be helpful to understand how to use a list and loop in the function.

# define a function
def my_fun(Skills):
    for x in Skills:
        print(x)

# call the function
my_fun(["Python", "R", "SQL"])

Output:

Python
R
SQL

Another Example

def my_fun(Skills):
    for x in Skills:
        print(x)

Languages = ["Python", "R", "SQL"]

# call the function
my_fun(Languages)

Output:

Python
R
SQL

Return in Function

You should use the return keyword in the following situation.

# define a function
def my_fun(a):
    return 5 * a

# call the function
print(my_fun(5))
print(my_fun(10))

Output:

25
50

If you will not use return then the output will be:

# define a function
def my_fun(a):
    5 * a

# call the function
print(my_fun(5))
print(my_fun(10))

None
None

I highly recommend you get the “Python Crash Course Book” to learn Python.