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

## Interview question
It is often useful to have default values in a hash. We might even want to make a bookmark since we can use this trick while solving interview questions. We’ll take a look at one of these questions.
 
Given a sentence, calculate the usage frequency for each word. For example, there are two  “the” words in the sentence, one “dog,” and so on. How do we solve this problem?
 
Imagine we have the string `"the quick brown fox jumps over the lazy dog"`. Let’s split this string into an array, so we have an array of words for this sentence:

```ruby
str = 'the quick brown fox jumps over the lazy dog'
arr = str.split(' ')   
```

We now have an array of words in the `arr` variable. Let’s traverse the array and put each element into a hash, where the hash key is the word itself and the value is the counter. As the first step, we will just set this counter to a single 1 for every word:

```ruby
hh = {}
arr.each do |word|
  hh[word] = 1
end
```

However, we don’t want to set the counter to a single `1` since we want to calculate the number of occurrences of every word in a sentence. So, we need to increase the counter by one. We can just use `hh[word] += 1` or `hh[word] = hh[word] + 1` because if the word is not present in the hash, we’ll get the following error:

```ruby
NoMethodError: undefined method '+' for nil:NilClass
```
In other words, the `plus` operation isn’t applicable to `nil`. So we need to perform a comparison: if the word is already in the hash, increase the counter by one. Otherwise, add this word with initial counter value, which is `1`:

```ruby
arr.each do |word|
  if hh[word].nil?
    hh[word] = 1
  else
    hh[word] += 1
  end
end
```

Here is what a full application listing would look like:

# Interview question
It is often useful to have default values in a hash. We might even want to make a bookmark since we can use this trick while solving interview questions. We’ll take a look at one of these questions.
 
Given a sentence, calculate the usage frequency for each word. For example, there are two  “the” words in the sentence, one “dog,” and so on. How do we solve this problem?
 
Imagine we have the string `"the quick brown fox jumps over the lazy dog"`. Let’s split this string into an array, so we have an array of words for this sentence:

```ruby
str = 'the quick brown fox jumps over the lazy dog'
arr = str.split(' ')   
```

We now have an array of words in the `arr` variable. Let’s traverse the array and put each element into a hash, where the hash key is the word itself and the value is the counter. As the first step, we will just set this counter to a single 1 for every word:

```ruby
hh = {}
arr.each do |word|
  hh[word] = 1
end
```

However, we don’t want to set the counter to a single `1` since we want to calculate the number of occurrences of every word in a sentence. So, we need to increase the counter by one. We can just use `hh[word] += 1` or `hh[word] = hh[word] + 1` because if the word is not present in the hash, we’ll get the following error:

```ruby
NoMethodError: undefined method '+' for nil:NilClass
```
In other words, the `plus` operation isn’t applicable to `nil`. So we need to perform a comparison: if the word is already in the hash, increase the counter by one. Otherwise, add this word with initial counter value, which is `1`:

```ruby
arr.each do |word|
  if hh[word].nil?
    hh[word] = 1
  else
    hh[word] += 1
  end
end
```

Here is what a full application listing would look like:

Learn how to set default values in a hash 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

Setting a Default Value in Hash

Interview question