Working with Libraries

As we’ve seen in our Functions and Modularity lesson, breaking code into reusable pieces makes programming more efficient. But what if someone else has already written code that solves your problem? That’s where libraries come in!

What is a Library?

A library is a collection of pre-written code that helps you perform common tasks without having to write everything from scratch. Libraries save time and reduce errors by providing tested and optimized functionality.

For example, instead of writing your own code to generate random numbers, you can use a library that already provides this feature.

Importing Libraries

Most programming languages allow you to import libraries to use their functions.

Python Example: Using the math Library

import math

print(math.sqrt(25))  # Outputs: 5.0
print(math.pi)        # Outputs: 3.141592653589793

JavaScript Example: Using Math

console.log(Math.sqrt(25)); // Outputs: 5
console.log(Math.PI); // Outputs: 3.141592653589793

In Python, we explicitly import the math module. In JavaScript, the Math object is built-in, so no import is needed.

Installing External Libraries

Some libraries are built-in, meaning they come with the programming language. Others need to be installed separately.

Installing a Library in Python

Python uses a package manager called pip to install libraries.

pip install requests

Now you can use the requests library to fetch data from the internet:

import requests
response = requests.get("https://api.github.com")
print(response.status_code)  # Outputs: 200

Installing a Library in JavaScript (Node.js)

JavaScript uses npm (Node Package Manager) to install libraries.

npm install axios

Now you can use axios to fetch data:

const axios = require("axios");
axios.get("https://api.github.com").then((response) => {
  console.log(response.status);
});

Finding the Right Library

There are thousands of libraries available! Here’s where to find them:

When choosing a library, consider:

  • Popularity – More users usually mean better support.
  • Documentation – Good libraries have clear guides and examples.
  • Compatibility – Ensure it works with your project.

Why Use Libraries?

  • Saves time – Avoid reinventing the wheel.
  • Reduces errors – Use battle-tested code.
  • Expands functionality – Work with data, graphics, networking, and more.

Summary

  • Libraries provide reusable code to make programming easier.
  • You can import built-in libraries or install external ones.
  • Use package managers like pip (Python) or npm (JavaScript) to install libraries.
  • Always check documentation to learn how to use a library effectively.

Next Steps

Try using a library in your next project! Start by exploring the built-in libraries in your language and experiment with installing new ones.

Have a favorite library? Share it in the comments!

Happy coding!