Functions vs Methods

As I continue learning Python, I’m using these study notes to summarise key concepts I come across. Today’s focus is on functions vs. methods — two fundamental concepts in Python programming.

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What is a Function?

A function is a reusable block of code that performs a specific task. It is independent and can be called anywhere in the program.

Example of a Function:

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

result = add_numbers(5, 10)  
print(result)  # Output: 15

What is a Method?

A method is a function that is associated with an object and belongs to a class. It typically operates on data stored in the object.

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Example of a Method:

class Calculator:  
    def add(self, a, b):  
        return a + b  

calc = Calculator()  
result = calc.add(5, 10)  
print(result)  # Output: 15

🔹 Here, add() is a method because it belongs to the Calculator class and must be called using an instance (calc).

What are the Key Differences?

Example of Both Function and Method:

# Function (independent)
def greet(name):
    return "Hello, {name}!"

print(greet("Alice"))  # Output: Hello, Alice!

# Method (inside a class)
class Person:
    def __init__(self, name):
        self.name = name
    
    def greet(self):  # Method
        return "Hello, {self.name}!"

p = Person("Bob")
print(p.greet())  # Output: Hello, Bob!

🔹 greet(name) is a function because it is independent.
🔹 greet() inside Person class is a method because it belongs to an object (p).

Conclusion

Functions are standalone, while methods belong to objects and typically modify or interact with an object’s data. Both are powerful tools that help make Python code reusable and structured.