rubytarball.tar.gz

Do you want to be an interpreted language geek? Are you tired of getting entangled in the dense syntaxes? Does it irritate you to compile your code to machine language first? Are you looking for an easy-to-use scripting language? Well, Ruby is the best pick for you then!

Ruby is a smart, easy-to-use, functional, Object-Oriented programming language, which comes as a wondrous mix of Perl's scripting power, Pythonic capabilities and much more! As Matsumoto, creator of Ruby, implies: "I hope to see Ruby help every programmer in the world to be productive, and to enjoy programming, and to be happy. That is the primary purpose of Ruby language."

This introductory course will be providing you with hands-on practice with the support of a bunch of interactive illustrations, exercises and the integral topics of variables, built-in classes, objects, conditionals, blocks and much more!

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

Ruby: An Amateur's Pitch

# *If this is true, then do that. Otherwise, do something else.* 

Often we want to check for a certain condition, and then based on it, do
either one thing or another. Or we want to do something only if a condition is
true.

All practical programming languages have some way of expressing this, and in
Ruby it looks like so:

number = 5

if number.between?(1, 10)
  puts "The number is between 1 and 10"
elsif number.between?(11, 20)
  puts "The number is between 11 and 20"
else
  puts "The number is bigger than 20"
end


You can probably guess what it does, and how it works, can't you?

# Explanation
Let's walk through it one by one:

* If you run this code it will print out `The number is between 1 and 10`,
  because the number assigned to the variable `number` on the first line is
  `5`, and for this number the method call `number.between?(1, 10)` returns
  `true`. Ruby will therefore execute the code in the `if` branch: The `if`
  branch is the block of code that comes after the line with the `if`
  statement, and that is indented by two spaces. Once it is done executing
  the `if` branch Ruby will simply ignore the rest of the statement.

* If you change the number `5` on the first line to `15`, and run the code
  again, then it will print out `The number is between 11 and 20`. In this
  case Ruby will, again, first check the first condition `number.between?(1,
  10)`, but this time this method call returns `false`. Therefore, Ruby will
  ignore the `if` branch, and check the next condition on the `elsif` line:
  `number.between?(11, 20)`. Now, this method call returns true, because `5` is
  between `11` and `20`. Ruby will therefore execute the `elsif` branch, and
  print out this message. Again, once it is done executing the `elsif` branch
  Ruby will ignore the rest of the statement.

* If you now change the number `15` to `25`, and run the code again, then it
  will print out `The number is bigger than 20`. Again, Ruby will first check
  the first condition, and find it returns `false`. It will check the second
  condition, which now also returns `false`. Therefore Ruby will then execute
  the `else` branch, and print out that message.

## `elsif` and `else` Statements
The `elsif` and `else` statements and branches are optional: you don't need to
have them. You can have an `if` statement without `elsif` or `else` branches,
an `if` statement only with an `else`, or you could have an `if` statement with
one or more `elsif` statements. Or combine all of them together:

|   There *must* be an `if` statement and branch.  |
| --- |

|    There *can* be many `elsif` statements and branches.  |
| --- |

|  There *can* be one `else` statement and branch.|
| --- |



This lesson gives an insight into conditionals in Ruby and their usage.

What are Conditionals?

If this is true, then do that. Otherwise, do something else.