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

# Casting data types example#


Let’s write a program to calculate our age in months. We’ll ask for the age in years, and our program will multiply this number by 12. Based on our knowledge from previous chapters, we should have something like this:


> **Note**: To run the program below, we will give our `age` as input using STDIN.


# Example program to convert age into month

puts "Your age?"
age = gets # Get age as input from user
age_months = age * 12
puts "Your age is " + age_months

Uh-oh! There definitely must be some mistake. It turns out that we need to multiply a _string_ by a number (_integer_). Try to run this program again and type `blabla`:



# Example program to understand string multiplication

puts "Your age?"
age = gets
age_months = age * 12
puts "Your age is " + age_months

## Explanation
The age variable is a type of string. When we multiply a string by an integer, the result is a very long string: a short string of `“blabla”`, repeated 12 times. To fix this program, we should multiply integer by integer. We already did this before when we calculated the number of milliseconds in a day. This time we just need to convert, or “cast”, type string into integer.

How can we do that? A quick documentation search for the gets function,  or `gets` method, will show that this function returns results with a type of string. This is understandable, because the `gets` function is “get string.” What we need now is the “get integer” function. And if we believe in Ruby’s principle of least surprise, it should be `geti`. Let’s check that:

```ruby
$ irb
>> geti

NameError (undefined local variable or method 'geti' for main:Object Did you mean? gets)
```
Oops! It didn’t work. But, it was a nice try. There is no such method as `geti`, but it may be implemented one day. Let’s think of other ways to fix our program.

There is one way to convert a string into a number in JavaScript. The trick is to multiply a string by 1. The node given below is a JavaScript interpreter, and it works if Node.js is installed on our computer:


```js
$ node
> "123" * 1 
123
```

Can we do the same trick in Ruby? Let’s try.


Learn to convert one data type into another 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

Type Casting (Type Conversion)

Casting data types example#