Geeks for geeks python functions

Python Functions is a block of statements that return the specific task.

The idea is to put some commonly or repeatedly done tasks together and make a function so that instead of writing the same code again and again for different inputs, we can do the function calls to reuse code contained in it over and over again. 

Syntax: Python Functions 

Creating a Python Function

We can create a  Python function using the def keyword.

Python3

def fun[]:

  print["Welcome to GFG"]

Calling a  Python Function

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

Python3

def fun[]:

    print["Welcome to GFG"]

fun[]

Output:

Welcome to GFG

Defining and calling a function with parameters

If you have experience in C/C++ or Java then you must be thinking about the return type of the function and data type of arguments. That is possible in Python as well [specifically for Python 3.5 and above].

Syntax: Python Function with parameters 

 def function_name[parameter: data_type] -> return_type:
    """Doctring"""
    # body of the function
    return expression

The following example uses arguments that you will learn later in this article so you can come back on it again if not understood. It is defined here for people with prior experience in languages like C/C++ or Java.

Python3

def add[num1: int, num2: int] -> int:

    num3 = num1 + num2

    return num3

num1, num2 = 5, 15

ans = add[num1, num2]

print[f"The addition of {num1} and {num2} results {ans}."]

Output:

The addition of 5 and 15 results 20.

Some more examples are as follows:

Note: The following examples are defined using syntax 1, try to convert them in syntax 2 for practice.

Python3

def is_prime[n]:

    if n in [2, 3]:

        return True

    if [n == 1] or [n % 2 == 0]:

        return False

    r = 3

    while r * r