Functions and Modules.md

Functions and Modules

Functions are reusable blocks of code that perform specific tasks, while modules are collections of functions and variables that can be imported and used in your code.

Defining and Calling Functions:

Functions are defined using the def keyword in Python. They allow us to organize our code into logical blocks and perform specific tasks. Here's the basic syntax for defining a function:

def function_name(parameter1, parameter2, ...):
    # code block
    # perform some operations
    return result

Let's see an example:

# Example of a function
def greet(name):
    message = "Hello, " + name + "!"
    return message

# Calling the function
print(greet("Alice"))

In this example, we defined a function called greet that takes a name parameter. Inside the function, we create a message by concatenating the name parameter with a greeting. The return statement is used to return the result from the function. We then call the function greet("Alice") and print the returned message.

Parameters and Return Values:

Functions can accept parameters, which are values passed into the function when it is called. Parameters allow us to provide inputs to functions and make them more flexible. Functions can also return values using the return statement.

# Example of a function with parameters and return value
def add_numbers(a, b):
    result = a + b
    return result

# Calling the function
sum = add_numbers(3, 5)
print(sum)  # Output: 8

In this example, the function add_numbers takes two parameters, a and b, and returns their sum. We call the function with the arguments 3 and 5, and the returned result is assigned to the variable sum.

Importing Modules and Using Built-in Modules:

Modules are files containing Python code that can be used in other programs. Python provides a rich set of built-in modules that offer additional functionality beyond what is available in the standard Python library. We can import modules using the import statement.

# Example of importing and using a module
import math

radius = 5
area = math.pi * math.pow(radius, 2)
print(area)  # Output: 78.53981633974483

In this example, we import the math module, which provides various mathematical functions and constants. We use the math.pi constant and the math.pow() function to calculate the area of a circle with a given radius.

You can also import specific functions or variables from a module:

# Example of importing specific functions from a module
from math import sqrt, pow

result = pow(2, 3)
print(result)  # Output: 8.0

result = sqrt(25)
print(result)  # Output: 5.0

In this case, we import only the sqrt and pow functions from the math module, allowing us to use them directly without referencing the module name.