Python Functions - GeeksforGeeks

Python functions are reusable blocks of code used to perform a specific task. They help organize programs into smaller sections and execute the same logic whenever needed by calling the function.

use_of_function_in_javascript_12 — Functions in Python

Defining a Function

A function can be defined using def keyword. Below is the syntax to define a function:

Here, we define a function using def that prints a welcome message when called.

Python

def fun():
    print("Welcome to GFG")

Calling a Function

After creating a function, call it by using the name of the functions followed by parenthesis containing parameters of that particular function.

Python

def fun():
    print("Welcome to GFG")
    
fun()

Output

Welcome to GFG

Function Arguments

Arguments are values passed to a function when it is called. They allow functions to receive input data and perform operations using those values.

Syntax

def function_name(arguments):
# function body
return value

def function_name(arguments): defines a function with optional arguments.
# function body contains the statements to be executed.
return value returns a result from the function. If no return statement is used, it returns None by default.

Example: In this example, function checks whether the number passed as an argument is even or odd.

Python

def evenOdd(x):
    if (x % 2 == 0):
        return "Even"
    else:
        return "Odd"

print(evenOdd(16))
print(evenOdd(7))

Output

Even
Odd

Types of Function Arguments

Python supports different types of arguments that can be passed during a function call.

1. Default argument: Default argument use a predefined value when no value is passed during the function call.

Python

def myFun(x, y=50):
    print("x: ", x)
    print("y: ", y)

myFun(10)

Output

x:  10
y:  50

Explanation:

y=50 sets a default value for parameter y and myFun(10) passes only one argument.
Since y is not provided, it uses the default value 50.

2. Keyword Arguments: pass values using parameter names, so argument order does not matter.

Python