BLOC Loops

each_with_index rdoc

each_with_index {|obj, i| block } → enum click to toggle source
Calls block with two arguments, the item and its index, for each item in enum.

hash = Hash.new
%w(cat dog wombat).each_with_index {|item, index|
  hash[item] = index
}
hash   #=> {"cat"=>0, "wombat"=>2, "dog"=>1}

Loops

#CP1

class Array
  def sum_numbers
    sum_numbers=0
    self.each do |num|
      sum_numbers+=num
    end
    sum_numbers
  end 

#RSpec

describe "Array" do
  describe "sum_numbers" do
    it "sums consecutive numbers" do
      [1,2,3].sum_numbers.should eq(6)
    end
    it "sums random numbers" do
      [5,23,4].sum_numbers.should eq(32)
    end
  end
end

#CP1 2

  def add_index
      self.each_with_index do |item, index|
        addIndexToElements << "#{index} is #{item}"
      end
      addIndexToElements
    end
end

#RSpec

describe "Array" do
  describe "add_index" do
    it "adds index to numbers" do
      [1, 2, 3].add_index.should eq(["0 is 1", "1 is 2", "2 is 3"])
    end
    it "adds index to strings" do
      new_array = ["0 is apple", "1 is banana", "2 is orange"]
      ["apple", "banana", "orange"].add_index.should eq(new_array)
    end
  end
end

#CP1 3

class String
  def camel_case
    camelCaseArray = []
    self.split.each_with_index do |item, index|   
      if index == 0
        camelCaseArray << item.downcase
      else
        camelCaseArray << item.capitalize  
      end
    end
    camelCaseArray.join
  end
end

#RSpec

describe "String" do
  describe "camel_case" do
    it "leaves first word lowercase" do
      "test".camel_case.should eq("test")
    end
    it "should lowercase first letter if it isn't" do
      "Test".camel_case.should eq("test")
    end
    it "should combine words using camel case" do
      "This is a test".camel_case.should eq("thisIsATest")
    end
    it "should downcase words with capitals" do
      "MUST dOWNCASE words".camel_case.should eq("mustDowncaseWords")
    end
  end
end

#CP2
 class String
  def title_case
    fixTitle = []
    self.split.each_with_index do |item, index|  
      downcase = item.downcase          
      if ((downcase == "and" || downcase == "a" || downcase == "the" || downcase == "of") && index != 0)
        fixTitle << downcase
      else
        fixTitle << item.capitalize
      end
    end  
    fixTitle.join(" ")
  end   
end

#RSpec
describe "String" do
  describe "Title case" do
    it "capitalizes the first letter of each word" do
      "the great gatsby".title_case.should eq("The Great Gatsby")
    end
    it "works for words with mixed cases" do
      "liTTle reD Riding hOOD".title_case.should eq("Little Red Riding Hood")
    end
    it "ignores articles" do
      "The lord of the rings".title_case.should eq("The Lord of the Rings")
      "the sword and the stone".title_case.should eq("The Sword and the Stone")
      "the portrait of a lady".title_case.should eq("The Portrait of a Lady")
    end
    it "works for strings with all uppercase characters" do
      "THE SWORD AND THE STONE".title_case.should eq("The Sword and the Stone")
    end
  end
end

working irb

#Notes that are a good reference for working with irb (else)

1.9.3-p392 :003 > 1+2
 => 3
1.9.3-p392 :004 > class Foo
1.9.3-p392 :005?>   def foo
1.9.3-p392 :006?>     print 1
1.9.3-p392 :007?>     end
1.9.3-p392 :008?>   end
 => nil
1.9.3-p392 :009 > a = [1,2,3,4]
 => [1, 2, 3, 4]
1.9.3-p392 :010 > a.each do |num|
1.9.3-p392 :011 >     p "The num argument is assigned to: #{num}"
1.9.3-p392 :012?>   end
"The num argument is assigned to: 1"
"The num argument is assigned to: 2"
"The num argument is assigned to: 3"
"The num argument is assigned to: 4"
 => [1, 2, 3, 4]
1.9.3-p392 :013 > a = ["job", "getting", "better", "millionaire"]
 => ["job", "getting", "better", "millionaire"]
1.9.3-p392 :014 > a.each do |text|
1.9.3-p392 :015 >     p "The text argument is assigned to: #{text}"
1.9.3-p392 :016?>   end
"The text argument is assigned to: job"
"The text argument is assigned to: getting"
"The text argument is assigned to: better"
"The text argument is assigned to: millionaire"
 => ["job", "getting", "better", "millionaire"]
1.9.3-p392 :017 >

#Notes that are a good reference for working with irb (while)

server:~ holmertraining$ irb
1.9.3p392 :001 > names = ["Steve", "Bill", "Sergey"]
 => ["Steve", "Bill", "Sergey"]
1.9.3p392 :002 > index = 0
 => 0
1.9.3p392 :003 > while names[index]
1.9.3p392 :004?>   p names[index]
1.9.3p392 :005?>   index += 1
1.9.3p392 :006?>   end
"Steve"
"Bill"
"Sergey"
 => nil
1.9.3p392 :007 >