#### Overview of this book

Ruby is a powerful, general-purpose programming language that can be applied to any task. Whether you are an experienced developer who wants to learn a new language or you are new to programming, this book is your comprehensive Ruby coding guide. Starting with the foundational principles, such as syntax, and scaling up to advanced topics such as big data analysis, this book will give you all of the tools you need to be a professional Ruby developer. A few of the key topics are: object-oriented programming, built-in Ruby methods, core programming skills, and an introduction to the Ruby on Rails and Sinatra web frameworks. You will also build 10 practical Ruby programs. Created by an experienced Ruby developer, this book has been written to ensure it focuses on the skills you will need to be a professional Ruby developer. After you have read this book, you will be ready to start building real-world Ruby projects.
Preface
Free Chapter
Introduction to the Ruby Programming Language
Ruby Variables
Ruby Strings
Working with Numbers in Ruby
Ruby Iterators and Loops
Ruby Collections
Ruby Conditionals
Working with the Filesystem in Ruby
Error Handling in Ruby
Regular Expressions in Ruby
Searching with grep in Ruby
Ruby Gems
Ruby Web Frameworks
Working with APIs in Ruby
Machine Learning

# How to code a Fibonacci digit counter

In this section, we are going to solve another fun math problem that asks us to solve this problem: what is the index of the first term in the Fibonacci sequence to contain 1,000 digits?

In case your college algebra is a little rusty, the Fibonacci sequence is a series where you add the next number to the previous number in that series. These numbers can get massive quickly because the addition to the previous value creates a mathematical snowball effect.

Though the problem sounds daunting, it can be solved easily in Ruby.

We are going to start by creating a method called fibonacci_digit_counter and define some variables:

`def fibonacci_digit_counter  num1, num2, i = -1, 0, 1end `

Next, we will create a while loop inside of the fibonacci_digit_counter method and iterate over the digit value of i:

`while i.to_s.length < 1000  num1 += 1  i,...`