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Eloquent Ruby -- Digging in to Arrays and Strings

Part 1: Taking Advantage of Ruby's Smart Collections

First, read chapter 3 (pages 29 through 42).

Next, use what you've learned to solve these short challenges:

1. Using Variable Method Arguments

Write a method that takes any number of arguments, and prints the value of the first and last arguments, ignoring any middle ones.

For example, using this method from IRB or Pry might look like:

variable("first", "second", "third")
first
third
nil

2. Using Map and Join

  1. Create an array containing the strings "dog", "cat", "goat", and "capybara"
  2. Transform this array into a new array where each string is capitalized ("Dog", "Cat", "Goat", "Capybara")
  3. Combine this collection of capitalized strings into a single string, with each element separated by a comma and a space ("Dog, Cat, Goat, Capybara")

3. Dangers of ! Methods

  • Summarize in your own words the conventions around methods whose names end in a !
  • Describe in your own words the advantages and disadvantages of these methods. When would you want to use one and when would you want to avoid using one.

Part 2: Taking Advantage of Ruby's Smart Strings

First, read chapter 4 (pages 43 through 52).

Next, use what you've learned to solve these short challenges:

1. Special Characters in Strings

  • What does it mean to "escape" a character within a string?
  • List 3 characters that have to be "escaped" when written in a string.
  • Use escape strings to generate a string containing your name and, on a separate line, your height in inches and feet.

For example, mine, when printed, would look like:

Horace
5'9"

2. Splitting Strings

Take the string of your name and height you generated in the previous section and split it into an array containing your name (as the first element) and height (as the second element).

For example my example from above would generate:

["Horace", "5'9\""]

Don't forget that split takes an optional argument specifying the character on which you'd like to split your string.

3. Poking at Bytes

We know that ultimately all data on our computers has to get represented as numbers (numbers encoded as 1's and 0's, to be precise). So how does text fit into this representation?

In short, the machine uses tables that map characters to specific numeric values.

Use the each_byte method on a string to discover which numeric byte values correlate to each character in your name.

For example, "Horace" translates to:

[72, 111, 114, 97, 99, 101]