Gain insights into Ruby development with 78 tasks tailored for beginners and experienced coders. Explore object-oriented concepts, debug programs, and advance your freelance coding career.

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This self-study course written as a book is your first step towards making money by coding and programming from home, and having fun doing it. You will understand how the Ruby language works, and establish a foundation for being a successful freelance developer. This course gives you not only technical detail, but presents knowledge in a friendly format, understandable by all ages, providing a thorough explanation of modern concepts for absolute beginners.

In this course you will find 78 easy to follow tasks, so even people without any programming skill can solve them. Beginners will learn how to create, debug, and understand programs in Ruby. Those who are already familiar with the language will rediscover object-oriented concepts, memory organization, find career advice, and save the planet from a nuclear apocalypse.

Ready to dive into one of the most influential and demanding third generation programming languages? Let's tune in!

The Handbook for Ruby Developers

# How to access two-dimensional arrays

There is a trick while accessing two-dimensional arrays. When accessing this type of array, we need to access the row first and the column next. From the previous lessons, we learned how to access a one-dimensional array:


```ruby
puts arr[4]
```

Or, if we want to change the value:

```ruby
arr[4] = 123
```

Now, `4` is the index. With 2D arrays, we need to use double square brackets. For example, the following code will change the value of the cell in the fifth row and the ninth column:

```ruby
arr[4][8] = 123
```
For a long time in school, we were told that the coordinates of some area are usually defined as (x, y) in mathematics, where “x” is the position on a horizontal axis (a specific column), and “y” is a position on a  vertical axis (a specific row). However, accessing arrays is a bit confusing because we need to access the row first and the column next, or in other words, by using (y, x).

To get a better feeling of how it works, we can break down this expression into multiple lines:

```ruby
row = arr[4] # Get the entire array on fifth row into variable
row[8] = 123 # Change the ninth cell to 123
```
This is the way to print the value of the fifth row and the ninth column:


```ruby
row = arr[4] # Get entire row into variable
column = row[8] # Get the value of cell into another variable
puts column # Print this variable
```

Learn how to access two-dimensional arrays in Ruby.


Accessing Arrays of Arrays

Learn how to access two-dimensional arrays in Ruby.

Before We Begin

First Steps

Fundamentals of Ruby

Conditional Statements

Operators and Methods

Arrays

Hash

Fun with Object Oriented Programming

Debugging in Ruby

Ruby Version Manager

Testing Ruby Programs

Wrap Up!

Appendix

Accessing Arrays of Arrays

How to access two-dimensional arrays