some basic ruby refers to ruby-doc-1 reviews

 a = 'ten'
 => "ten"
2.3.1 :002 > "my favoutite number is #{a}!"
 => "my favoutite number is ten!"
2.3.1 :003 >
2.3.1 :029 > "john" + "Doe"
 => "johnDoe"
2.3.1 :030 > a = "Doe"
 => "Doe"
2.3.1 :031 > "John#{a}"
 => "JohnDoe"

# division
2.3.1 :013 > 15 / 4
 => 3
#modulo
2.3.1 :014 > 15 % 3
 => 0
2.3.1 :015 > 15 % 4
 => 3
#float
2.3.1 :016 > 15.0 / 4
 => 3.75
2.3.1 :017 > '4'.to_i
 => 4
2.3.1 :018 > '4'.to_f
 => 4.0
2.3.1 :019 > "4 here test".to_f
 => 4.0
2.3.1 :020 > "here test 4".to_f
 => 0.0

2.3.1 :021 > [1,2,3,4,][0]
 => 1
2.3.1 :022 > [1,2,3,4,][3]
 => 4

2.3.1 :023 > {:a => '1', :b => '2', :c => '3'}[a]
 => nil
2.3.1 :024 > {:a => '1', :b => '2', :c => '3'}[:a]
 => "1"

2.3.1 :032 > arr = [1,2,3]
 => [1, 2, 3]
2.3.1 :033 > arr.map { |a| 2*a}
 => [2, 4, 6]
2.3.1 :034 > arr
 => [1, 2, 3]
2.3.1 :035 > arr.map! {|a| 2*a }
 => [2, 4, 6]
2.3.1 :036 > arr
 => [2, 4, 6]
2.3.1 :037 > ['1','2','3'].map(&:to_i)
 => [1, 2, 3]
#same as
2.3.1 :038 > ['1','2','3'].map{ |i| i.to_i}
 => [1, 2, 3]

x = 0        
3.times do
  x += 1
end
puts x
#prints 3 to the screen
y = 0
3.times do
  y += 1
  x = y
end
puts x
# cant print, errors undefined local variable or method cuz x is not avaiavle as it is created with in the scope of the do/end block ,so its inner scope that's entirely outside of the execution flow.

#ruby name.rb
puts "What is your name?"
name = gets.chomp
puts "Hello " + name
#ruby name2.rb
puts "what is your first name?"
first_name = gets.chomp
puts "what is your last name?"
last_name = gets.chomp
puts "Great. so your full name is " + first_name + " " + last_name
#ruby age.rb notice .to_i 
puts "how old are you?"
age = gets.chomp.to_i
puts "in 10 years you will be:"
puts age + 10
puts "in 20 years you will be:"
puts age + 20