Python Functions

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

Functions help us:

• Avoid repeating code
• Organize code
• Reuse the same logic with different inputs

1. Creating a Function

In Python, a function is defined using the def keyword.

Syntax

1def function_name(parameters):
2    # function body

Example

1def greet():
2    print("Hello, Akash!")

The function does not run when it is defined. It runs when we call it.

1

Output:

1Hello, Akash!

2. Function Parameters

Parameters are variables that receive values when a function is called.

1def greet(name):
2    print("Hello", name)
3 
4greet("Akash")

Output:

1Hello Akash

Here:

• name → parameter
• "Akash" → argument

A function can have multiple parameters:

1def add(a, b):
2    print(a + b)
3 
4add(10, 20)

Output:

130

3. Return Value

A function can send a result back to the caller using return.

1def add(a, b):
2    return a + b
3 
4result = add(10, 20)
5 
6print(result)

Output:

130

return also stops the execution of the function.

If a function does not have a return statement, it returns None.

4. Arguments

Arguments are the actual values passed to a function.

1def greet(name):
2    print("Hello", name)
3 
4greet("Akash")

Here:

1name     → Parameter
2"Akash"  → Argument

Python supports different ways of passing arguments, such as:

• Positional arguments
• Keyword arguments
• Default arguments
• Variable-length arguments

5. Default Parameter

A parameter can have a default value.

1def greet(name="User"):
2    print("Hello", name)
3 
4greet()
5greet("Akash")

Output:

1Hello User
2Hello Akash

The default value is used when no argument is provided.

6. pass Statement

The pass statement is used when a function has no implementation yet.

1def my_function():
2    pass

It allows us to create an empty function without getting an error.

7. Why Use Functions?

Without a function:

1print("Hello Akash")
2print("Hello Rahul")
3print("Hello Priya")

With a function:

1def greet(name):
2    print("Hello", name)
3 
4greet("Akash")
5greet("Rahul")
6greet("Priya")

The second approach lets us write the logic once and reuse it.

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