Learn Ruby Exercises

00_hello/hello.rb

@@ -0,0 +1,7 @@
+def hello
+  "Hello!"
+end
+
+def greet(who)
+  "Hello, #{who}!"
+end

01_temperature/temperature.rb

@@ -0,0 +1,9 @@
+def ftoc(fahrenheit)
+  c = (fahrenheit - 32).to_f * 5/9
+  return c
+end
+
+def ctof(celcius)
+  f = (celcius.to_f * 9/5) + 32
+  return f
+end

02_calculator/calculator.rb

@@ -0,0 +1,37 @@
+def add(a,b)
+  a + b
+end
+
+def subtract(a,b)
+  a - b
+end
+
+def sum(array)
+  sum = 0
+  array.each do |i|
+    sum += i
+  end
+  sum
+end
+
+def multiply(array)
+  product = 1
+  array.each do |i|
+    product *= i
+  end
+  product
+end
+
+def power(a,b)
+  a**b
+end
+
+def factorial(n)
+  if n == 1
+    return 1
+  elsif n == 0
+    return 0
+  else
+    n * factorial(n - 1)
+  end
+end

02_calculator/calculator_spec.rb

@@ -79,21 +79,41 @@
 
 describe "#multiply" do
 
-  it "multiplies two numbers"
+  it "multiplies two numbers" do
+    expect(multiply([2,8])).to eq(16)
+  end
 
-  it "multiplies several numbers"
+  it "multiplies several numbers" do
+    expect(multiply([2,5,3,4])).to eq(120)
+  end
 
 end
 
 describe "#power" do
-  it "raises one number to the power of another number"
+  it "raises one number to the power of another number" do
+    expect(power(5,3)).to eq(125)
+  end
 end
 
 # http://en.wikipedia.org/wiki/Factorial
 describe "#factorial" do
-  it "computes the factorial of 0"
-  it "computes the factorial of 1"
-  it "computes the factorial of 2"
-  it "computes the factorial of 5"
-  it "computes the factorial of 10"
+  it "computes the factorial of 0" do
+    expect(factorial(0)).to eq(0)
+  end
+
+  it "computes the factorial of 1" do
+    expect(factorial(1)).to eq(1)
+  end
+
+  it "computes the factorial of 2" do
+    expect(factorial(2)).to eq(2)
+  end
+
+  it "computes the factorial of 5" do
+    expect(factorial(5)).to eq(120)
+  end
+
+  it "computes the factorial of 10" do
+    expect(factorial(10)).to eq(3628800)
+  end
 end

03_simon_says/simon_says.rb

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+def echo(str)
+  str
+end
+
+def shout(str)
+  str.upcase
+end
+
+def repeat(str, num = 2)
+  phrase = ""
+  until num == 0
+    phrase += str
+    phrase += " "
+    num -= 1
+  end
+  phrase.strip
+end
+
+def start_of_word(word,num_letters)
+  word.slice(0, num_letters)
+end
+
+def first_word(str)
+  str.split(' ').first
+end
+
+def titleize(str)
+  small_word = ['and','over','the']
+  str_array = str.split(' ')
+  str_array.each_with_index do |i, index|
+    if index == 0
+      i.capitalize!
+    elsif small_word.include?(i)
+      i
+    else
+      i.capitalize!
+    end
+  end
+  str_array.join(' ')
+end

04_pig_latin/pig_latin.rb

@@ -0,0 +1,61 @@
+require 'pry'
+def translate(str)
+
+  str.downcase!
+  # split string into words
+  words = split_str(str)
+
+  # split word into letters
+  letters = split_words(words)
+
+  # until reach a vowel (unless qu), unshift consonants
+  # and push those consonants to an end_of_word array
+  # append the end_of_word array to the array
+  # append the 'ay' array to the array
+  pig_latinned_arrays = move_consonants(letters)
+
+  # join the letters array
+  # join the word array
+  # return the array
+  pig_latinned_string = join_arrays(pig_latinned_arrays)
+  return pig_latinned_string
+
+end
+
+def split_str(str)
+  str.split(' ')
+end
+
+def split_words(words)
+  letters = words.map do |word|
+    word.split('')
+  end
+  letters
+end
+
+def move_consonants(letters)
+  vowels = ['a','e','i','o','u']
+  ay = ['a','y']
+  letters.each do |word|
+      consonants_array = []
+    until vowels.include?(word[0])
+      if word[0] == 'q' && word[1] == 'u'
+        2.times do |i|
+          consonants_array << word.shift
+        end
+      else
+        consonants_array << word.shift
+      end        
+    end
+    word.concat(consonants_array).concat(ay)
+  end
+  letters
+end
+
+def join_arrays(pig_latinned_arrays)
+  joined_words = []
+  pig_latinned_arrays.each do |word|
+    joined_words << word.join('')
+  end
+  joined_words.join(' ')
+end

05_silly_blocks/silly_blocks.rb

@@ -0,0 +1,19 @@
+def reverser
+  split_string = yield.split(' ')
+  split_string.map do |word|
+    word.reverse!
+  end
+  result = split_string.join(' ')
+  result
+end
+
+def adder(num = 1)
+  result = yield + num
+  result
+end
+
+def repeater(num = 1)
+  num.times do |i|
+    yield
+  end
+end

06_performance_monitor/performance_monitor.rb

@@ -0,0 +1,8 @@
+def measure(num_loops = 1)
+  start_time = Time.now
+  num_loops.times do
+    yield
+  end
+  end_time = Time.now
+  (end_time - start_time) / num_loops
+end

07_hello_friend/friend.rb

@@ -0,0 +1,9 @@
+class Friend
+  def greeting(who = nil)
+    if who == nil
+      "Hello!"
+    else
+      "Hello, #{who}!"
+    end
+  end
+end

08_book_titles/book.rb

@@ -0,0 +1,21 @@
+class Book
+
+  def title=(title)
+    lowercase_words = ['the','a','an','and','in','of']
+    word_array = title.split(' ')
+    word_array.map do |word|
+      if lowercase_words.include?(word)
+        word
+      else
+        word.capitalize!
+      end
+    end
+    word_array[0].capitalize!
+    @title = word_array.join(' ')
+  end
+
+  def title
+    @title
+  end
+
+end

09_timer/timer.rb

@@ -0,0 +1,46 @@
+
+# what we're trying to do here is create an object "Timer" with a seconds method that takes the number of seconds elapsed, and a time_string method that returns in hour: minute: second format
+
+require 'pry'
+
+class Timer
+
+  def initialize(s = 0, m = 0, h = 0)
+    @seconds = s
+    @minutes = m
+    @hours = h
+  end
+
+  def seconds
+    @seconds
+  end
+
+  def seconds=(number)
+    @seconds = number
+  end
+
+  def time_string
+    calculate_clock_time
+    make_time_read_friendly
+  end
+
+end
+
+def calculate_clock_time
+  if @seconds > 60
+    @minutes = @seconds / 60
+    @seconds -= @minutes * 60
+  end
+  if @minutes > 60
+    @hours = @minutes / 60
+    @minutes -= @hours * 60
+  end
+end
+
+def make_time_read_friendly
+  time_array = [@hours.to_s,@minutes.to_s,@seconds.to_s]
+  time_array.map do |time|
+    time.prepend('0') until time.length == 2
+  end
+  time_array.join(':')
+end

10_temperature_object/temperature.rb

@@ -0,0 +1,45 @@
+require 'pry'
+class Temperature
+
+  def initialize(temperatures = {:f => nil, :c => nil })
+    @fahrenheit = temperatures[:f]
+    @celsius = temperatures[:c]
+  end
+
+  def in_fahrenheit
+    if @fahrenheit
+      @fahrenheit
+    else
+      (@celsius.to_f * 9/5).to_f + 32.to_f
+    end
+  end
+
+  def in_celsius
+    if @celsius
+      @celsius
+    else
+      (@fahrenheit.to_f - 32).to_f * 5/9.to_f
+    end
+  end
+
+  def self.from_celsius(c)
+    self.new(:c => c)
+  end
+
+  def self.from_fahrenheit(f)
+    self.new(:f => f)
+  end
+
+end
+
+class Celsius < Temperature
+  def initialize(c)
+    @celsius = c
+  end
+end
+
+class Fahrenheit < Temperature
+  def initialize(f)
+    @fahrenheit = f
+  end
+end