Execute Ruby Online

#Message passing 
puts "the ruby language".length 
puts "Ruby".index("y")
puts -6.abs
puts 10.49.round
puts 10.50.round
puts 2.next
puts 99.chr
puts

#Variables and Aliasing 
person1 = "Tommy"
person2 = person1
#assigning person1 to person2 does not create an new objet. Both refer to the same object. 
puts person1
puts person2
puts

#To void aliasing, and create new object with same content use dup.
person3 = person1.dup 
person1[0] = "R"
puts person1 
puts person2
puts person3 #new object 
puts


#Chaining assignment statements 
#assignment sets variable on left to experssion on right. 
a = b = 1 + 2 + 3
puts a 
puts b 
puts

a = (b = 1 + 2) + 3 
puts a 
puts b 
puts 

#Parallel assigment 
a = 1 
b = 2 
a,b = b,a
puts a 
puts b 
puts 

x = 0 
a, b, c = x, (x += 1), (x +=1)
puts a   # x = 0
puts b   # x = 0 + 1  now x = 1 
puts c   # x = 1 + 1  now x = 2
puts x   # x = 2 
puts 

#Arrays 
#using literals : list of objects between brackets
#arrays can hold objects of different types 
a = ["number",1,2,3.14]
puts a
puts a.length
puts a[0] 
a[3] = nil 
puts a 
puts 

#Array object 
#Ruby allows array range specification
myarray = [1,2,3,4,5,6]
puts myarray[0]   #1
puts
puts myarray[1,3] #i to j,including j
puts
puts myarray[1...3] #i to j,excluding j
puts
puts myarray[1..3] #i to j,including j
puts

#Negative index allowed
a = ["pi", 3.14, "prime",17]
puts a.class
puts a[-1]   #count from end of array
puts a[3]
puts a[-2]
puts a[2]
puts a[1]
puts a[0]
puts
b = Array.new
puts b.class
puts b.length
b[0]  = "a"
b[1]  = "new"
puts b.length
puts b
puts

#Associative Arrays (Hash)
#undordered collection of elements 
#element is a pair of two objects: 
#value and key:
#hashName = { "key" => "value",...}

biblio = { "hello" => "No",
           "Salut" => "Yes",
           "Tell me the gossip fam" => "maybe" }
           
puts biblio.length

#To retreive the value of a key:
#["key"] = value 
puts biblio["hello"]
biblio["Tell me the gossip fam"] = "ok"
puts biblio["Tell me the gossip fam"]
puts

#Add to the collection
biblio["Someone is in love"] = "yas"
puts biblio["Someone is in love"]
puts biblio.length

#Delete an element 
biblio.delete_if{|key, value| key == "hello"}
puts biblio.length
puts

#Iterate over an associative array 
biblio.each_pair do |key,value|
 puts "#{key} : #{value}"
end
puts 

#Same output different way
biblio.each { |key, value| puts key + " : " + value}
puts

#Iterate over collection and access and disply each key individually
biblio.each_key {|key| puts key}