data-types

Last updated May 31, 2022.

# Metadata

2022-05-25 20:30

Data Types

# Content

It’s important to keep in mind that when doing arithmetic with two integers in Ruby, the result will always be an integer.

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17 / 5    #=> 3, not 3.4

To obtain an accurate answer, just replace one of the integers in the expression with a float.

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17 / 5.0  #=> 3.4

.to_f .to_i .even? .odd? Concatenation In true Ruby style, there are plenty of ways to concatenate strings.

# With the plus operator:

“Welcome " + “to " + “Odin!” #=> “Welcome to Odin!”

# With the shovel operator:

“Welcome " « “to " « “Odin!” #=> “Welcome to Odin!”

# With the concat method:

“Welcome “.concat(“to “).concat(“Odin!”) #=> “Welcome to Odin!”

.to_s

in Ruby, everything is an object

:my_symbol

string interpolation

“My favorite number is #{a}!”

symbol: immutable string

something about floats: the inaccuracies may be linked as to how, for example, in 3d games the further away you go from the point of origin, the more odd the graphics can get.

Hashes

A hash, sometimes referred to as a dictionary, is a set of key-value pairs. Hash literals are represented with curly braces { }. A key-value pair is an association where a key is assigned a specific value. A hash consists of a key, usually represented by a symbol, that points to a value (denoted using a =>) of any type of data. Let’s make some hashes to get the feel of it. Type along!

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irb :001 > {:dog => 'barks'}
=> {:dog => 'barks'}

hash rocket is =>

Expressions and Return

You may have noticed, indirectly at this point, that every time you enter something into irb you see the => back, which is called a hash rocket (cool name, huh?), followed by whatever your Ruby expression returns. When you type something in at the irb prompt you are creating an expression. An expression is anything that can be evaluated, and pretty much everything you write in Ruby is an expression. An expression in Ruby always returns something, even if that’s an error message or nil. We’ll talk in more depth about return as we move on, but remember that Ruby expressions always return a value, even if that value is nil or an error.

An OBJECT is a location in computer memory where you can store DATA (aka VALUES).

There are many kinds of objects, including String, Number, Array, Hash, Time, …

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bundle install

This folder contains a Gemfile, which tells bundle which gems to install locally and makes them available for use in that directory. In this case, we are installing RSpec, which is a popular Ruby testing framework.

so rspec is like jest for javascript

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"MyString".methods.sort

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"MyString".own_methods.sort

Numbers
- What are the basic arithmetic operators you can use on numbers?

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+-*/%`

What’s the difference between an integer and a float?

ints are 1 2 3 4 floats are 1.0 2.0 3.0 4.0

What method would you use to convert a float to an integer?

.to_i .to_f

-   [What method would you use to convert an integer to a float?](https://www.theodinproject.com/lessons/ruby-basic-data-types#converting-number-types)