Strings and Symbols
Download as KEY, PDF0 likes319 views
This document discusses strings and symbols in Ruby. It describes how to concatenate, interpolate, format and modify strings. It also covers iterating over strings using methods like each_char. The document explains that symbols represent names efficiently and are immutable and unique, unlike strings which can be modified and multiple string objects can have the same value.
![ACCESS A STRING’S
CHARACTERS
>> full_name[2,4]
=> "kihi"
>> full_name[4..6]
=> "hir"](https://image.slidesharecdn.com/ch3stringssymbolskeynote-110202125211-phpapp01/85/Strings-and-Symbols-8-320.jpg)
![RUBY 1.8
>> name = "Yukihiro”
=> "Yukihiro”
>> name[4]
=> 104
>> name[4].chr
=> "h"
>> name = " ”
=>"343201223343202223343201204343201241343
20221”
>> name[2]
=> 147](https://image.slidesharecdn.com/ch3stringssymbolskeynote-110202125211-phpapp01/85/Strings-and-Symbols-9-320.jpg)
![RUBY 1.9
>> name = "yukihiro”
=> "yukihiro”
>> name[4]
=> "h”
>> name = " ”
=> " ”
>> name[2]
=> " ”
>> name[0]
=> " "](https://image.slidesharecdn.com/ch3stringssymbolskeynote-110202125211-phpapp01/85/Strings-and-Symbols-10-320.jpg)
![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"](https://image.slidesharecdn.com/ch3stringssymbolskeynote-110202125211-phpapp01/85/Strings-and-Symbols-11-320.jpg)
Strings and Symbols
- 1. STRINGS AND SYMBOLS Sarah Allen
- 2. STRINGS • “I am a string!”
- 3. QUOTING STRINGS • Double quotes interpolate >> me = "double quotes are awesome” >> "I am a string withsdouble quotes.n #{me}" => "I am a string with double quotes.n double quotes are awesome" • Single quotes don’t interpolate >> 'I am a string withssingle quotes.n #{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"
- 5. STRING INTERPOLATION birthday = “January 5th” “My birthday is #{birthday}”
- 6. STRING FORMATTING: UPCASE >> full_name.upcase >> full_name.upcase! => "YUKIHIRO MATSUMOTO” => "YUKIHIRO MATSUMOTO" >> full_name >> full_name => "Yukihiro Matsumoto" => "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 = " ” =>"343201223343202223343201204343201241343 20221” >> name[2] => 147
- 10. RUBY 1.9 >> name = "yukihiro” => "yukihiro” >> name[4] => "h” >> name = " ” => " ” >> name[2] => " ” >> name[0] => " "
- 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
- 13. ITERATE OVER A STRING • each_line: process each line in a string haiku = "5n7n5n” haiku.each_line{|line| puts line} 5 7 5 each_char: process character each_byte: process each byte careful of 1.8.x and 1.9 differences >> word = " " >> word = " " => " " => " " >> word.each_char do |s| puts >> word.each_byte do | s end s| puts s end 227 129
- 14. 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
- 15. MORE STRING OPERATIONS full_name = "" => "" full_name << first_name => "Yukihiro" full_name << " " => "Yukihiro " full_name << last_name => "Yukihiro Matsumoto"
- 16. MORE STRING OPERATIONS "foo " * 3 => "foo foo foo "
- 18. 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.
- 19. 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
- 20. 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
- 21. 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