1. Class 3 Strings and Symbols

2. Strings “I am a string!”

3. Quoting Strings Double quotes interpolate >> me = "double quotes are awesome” >> "I am a string withdouble quotes. #{me}" => "I am a string with double quotes. double quotes are awesome" Single quotes don’t interpolate >> 'I am a string withsingle quotes. #{me}' => "I am a string withssingle quotes.n {me}"

4. Concatenating Strings first_name = "Yukihiro” last_name = "Matsumoto” full_name = first_name + " " + last_name => "Yukihiro Matsumoto" full_name = first_name << " " << last_name => "Yukihiro Matsumoto"

5. String Interpolation birthday = “January 5th” “My birthday is #{birthday}”

6. String Formatting: upcase >> full_name.upcase => "YUKIHIRO MATSUMOTO” >> full_name => "Yukihiro Matsumoto" >> full_name.upcase! => "YUKIHIRO MATSUMOTO" >> full_name => "YUKIHIRO MATSUMOTO"

7. More String Formatting >> full_name.downcase! => "yukihiro matsumoto" >> full_name.capitalize => "Yukihiro matsumoto" Making our own title case method: >> full_name.split.map {|w| w.capitalize}.join(" ") => "Yukihiro Matsumoto" We can also get title case using regex

8. Access a String’s Characters >> full_name[2,4] => "kihi" >> full_name[4..6] => "hir"

9. Ruby 1.8 >> name = "Yukihiro” => "Yukihiro” >> name[4] => 104 >> name[4].chr => "h" >> name = "こんいちわ” =>"43012343022343010443014143021” >> name[2] => 147

10. Ruby 1.9 >> name = "yukihiro” => "yukihiro” >> name[4] => "h” >> name = "こんいちわ” => "こんいちわ” >> name[2] => "い” >> name[0] => "こ"

11. Modifying a String >> full_name.slice!("hi") => "hi" >> full_name => "yukiro matsumoto" >> full_name["hi"] = "bye" => "bye" >> full_name => "Yukibyero Matsumoto" >> full_name[4,2] = "bye" => "bye" >> full_name => "Yukibyero Matsumoto"

12. Query a String >> full_name.include?("hi") => true >> full_name.empty? => false >> full_name.size => 18 >> full_name.count("o") => 3

14. each_char: process charactercareful of 1.8.x and 1.9 differences>> word = "こにちわ" => "こにちわ" >> word.each_byte do |s| puts s end 227 129 >> word = "こにちわ" => "こにちわ" >> word.each_char do |s| puts s end こ に ち わ

15. Iterate Using Split returns an array of partial strings exploded at a separator secret_code = "the black dove flies at night” secret_code.split(" ").each do |s| puts s.reverse end eht kcalb evod seilf ta thgin

16. Symbols :i_am_a_symbol

17. What is a Symbol? A symbol represents a name. Instances of the built-in class Symbol. They efficiently describe names while saving the space one would use to generate a string for each naming instance.

18. A Symbol is not a String :thing != “thing” However a symbol can be create from a string: “thing”.to_sym And a string can be created from a symbol :thing.to_s

19. Symbols are Immutable You can’t change a symbol For example, you can’t append characters to a symbol...once a symbol exists, that’s it! >> :name + :me NoMethodError: undefined method `+' for :name:Symbol from (irb):182 from :0 >> :name << :me NoMethodError: undefined method `<<' for :name:Symbol from (irb):183 from :0

20. Symbols are Unique :name is the only symbol object called :name >> :name.object_id => 68828 >> :name.object_id => 68828 “name” is a new String object each time it is instantiated >> "name".object_id => 2157595700 >> "name".object_id => 2157591380

21. Homework Chapters: 8.1 & 8.2 11.1 – 11.8 Koans: about_strings Test-first-teaching piglatin