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Functions in Python

DEV Community [Unofficial] July 2, 2026
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What is a Function?

  • A function is a block of reusable code that performs a specific task.

Why Use Function?

  • Reuse code multiple times

  • Improve code readability

  • Reduce code duplication

  • Make programs easier to maintain

Syntax:

def function_name():
    <statement>

Example:

def greet():
    print("Hello, Python!")

greet()

Output:

Hello, Python!

Three types of Functions:

  • Function without Parameters

  • Function with Parameters

  • Function with return values

Function without Parameters:

A function that does not accept any input values is called a function without parameters.

Example:

def greet():
     print("Hello, Python!")

greet()

Output:

Hello, Python!

Function with Parameters:

A function that accepts input values is called a function with parameters.

Syntax:

def function_name(parameter):
     <statement>

Example:

def greet(name):
     print("Hello", name)

greet("World")

Output:

Hello World

Function with Return Value:

A function that returns a values using the return statement.

Example:

def add(a, b):
    return a + b

result = add(10,20)
print(result)

Output:

30

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