Python Function

In Python, a function is a block of code that performs a specific task. Functions help break down large programs into smaller, more manageable pieces, and allow you to reuse code across multiple parts of a program.

Here's the basic syntax for defining a function in Python:

def function_name(parameters):
    # function body
    # return statement (optional)

The def keyword is used to define a function. This is followed by the name of the function, parentheses, and a colon. Any parameters that the function takes should be listed in the parentheses. The body of the function is indented below the first line, and contains the code that performs the specific task of the function. Optionally, the function can return a value using the return statement.

Here's an example of a simple function that takes two parameters and returns their sum:

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

In this example, the function add_numbers takes two parameters a and b, and returns their sum. The body of the function calculates the sum and stores it in the variable result, then returns the value of result.

You can call the function by its name, passing in arguments for the parameters:

sum = add_numbers(3, 4)
print(sum)  # Output: 7

In this example, we call the function add_numbers with arguments 3 and 4. The return value of the function is stored in the variable sum, and then printed to the console.

Functions can also have default parameter values, allowing you to call the function with fewer arguments:

def greet(name, greeting='Hello'):
    print(greeting + ', ' + name + '!')

In this example, the function greet takes two parameters: name and greeting. The greeting parameter has a default value of 'Hello'. If you call the function with only one argument, the default value will be used:

greet('Alice')  # Output: Hello, Alice!

In this example, the function is called with only one argument, 'Alice'. The function uses the default value of 'Hello' for the greeting parameter. The output of the function call is 'Hello, Alice!'.