Python Functions

✨ Benefits of Using Functions

• Write code once, reuse it anywhere
• Makes debugging and testing easier
• Improves readability and structure
• Breaks complex problems into smaller steps

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🧱 Structure of a Python Function

def function_name(parameters):
    # code block
    return result  # optional

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✅ Example 1: Basic Function (No Parameters)

def greet():
    print("Hello!")
    
greet()  # Call the function

📤 Output:

Hello!

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✅ Example 2: Function With Parameters

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

greet("Alice")
greet("Ivan")

📤 Output:

Hello, Alice!
Hello, Ivan!

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✅ Example 3: Function With Return Value

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

result = add(3, 5)
print("The sum is:", result)

📤 Output:

The sum is: 8

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🔁 Example 4: Using a Function in a Loop

def square(x):
    return x * x

for i in range(5):
    print(square(i))

📤 Output:

0
1
4
9
16

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🧠 Notes

• Use def to define a function.
• Use return to send back a result.
• Functions can take 0 or more arguments.
• You can call a function as many times as needed.

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🛠️ Optional: Default Parameter Values

def greet(name="friend"):
    print("Hello, " + name)

greet()         # Uses default
greet("David")  # Overrides default

📤 Output:

Hello, friend
Hello, David

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