Personal Notes on Learning Ruby

Ruby notes.

First Ruby code

mkdir learnruby
cd learnruby
irb
2+3
5*40
25/2
25.0/2
25.class #Fixnum
25.0.class # Float
25.methods # [: to_s :-0, :+ ...etc.]
"Jimmy"
"Jimmy".reverse
"Jimmy"*5
def add_and_power a,b # or (a,b)
(a+b)**(a+b)
end # nil
add_and_power (2,3) # 3125
self # main
self.class # Object
self.methods # [:to_s, :public ....etc]
s1 = :foo
s2 = :foo
s1.equal? s2 # true
str1 = "Jimmy"
str2 = "Jimmy" 
str1 == str2 # true
str1.equal? str2 # false
# exit irb by ctrl+d


# creating first ruby file
vim add_and_power.rb
# in vim
def add_and_pwer a,b
(a+b)**(a+b)
end

input1 = gets
input2 = gets

puts add_and_power input1, input2

# save it and run ruby code
esc
:!w
:!ruby add_and_power.rb
# this gives an error
# You need to change input1 and 2 to integer
# change to 
puts add_and_power input1.to_i, input2.to_i

esc
:!w
:!ruby add_and_power.rb

# make it more interactive
# final code
def add_and_power a,b
(a+b)**(a+b)
end

puts *First number please? *
input1 = gets

puts *Second number please? *
input2 = gets

esc
:!w
:!ruby add_and_power.rb

Conditionals

Use if elsif, but watch out not elseif like php.

#1. ask for age

age = gets.to_i

#2. process

if age < 10
  puts "It's a young person."
elsif age < 19
  puts "It's a teen ager."
elsif age < 45
  puts "It's an adult."
elsif age < 95
  puts "It's an old person."
else
  puts "Is he dead?"
end

:w age.rb
:!ruby age.rb



# ex 2
output = if age < 10
      "it's a young person."
    elsif age < 19
      "it's a teen ager."
    elsif age < 45
      "it's an adult."
    elsif age < 95
      "it's an old person."
    else
      "is he dead?"
    end

puts output

Sublime text and Ruby

Use which ruby to find your default Ruby and use it in the following.

If you want to use sublime text build with Ruby, you need to change /Users/yourname/Library/Application Support/Sublime Text 2/Packages/Ruby/Ruby.sublime-build

{
    "cmd": ["/Users/yourname/.rbenv/shims/ruby", "$file"],
    "file_regex": "^(...*?):([0-9]*):?([0-9]*)",
    "selector": "source.ruby"
}

After installing SublimeREPL, you need to change /Users/yourname/Library/Application Support/Sublime Text 2/Packages/SublimeREPL/config/Ruby/Main.sublime-menu

For my case I chagned osx.

"cmd":{
        "windows":[
          "ruby.exe",
          "${packages}/SublimeREPL/config/Ruby/pry_repl.rb",
          "$editor"
        ],
        "linux":[
          "ruby",
          "${packages}/SublimeREPL/config/Ruby/pry_repl.rb",
          "$editor"
        ],
        "osx":[
          "/Users/yourname/.rbenv/shims/ruby",
          "${packages}/SublimeREPL/config/Ruby/pry_repl.rb",
          "$editor"
        ]

Written on July 5, 2013