Rubyの繰り返し処理の解説|初心者・独学者向け

greetings = ["こんにちは","おはよう","さよなら"]
greetings.each do |greeting|
  puts greeting
end

#実行結果
#こんにちは
#おはよう
#さよなら

nums = [1,2,3,4,5,6]
nums.each do |num|

  if num.odd?
    p "#{num}"+"は偶数です"
  else
    p "#{num}"+"は奇数です"
  end
end

#実行結果
# "1は奇数です"
# "2は偶数です"
# "3は奇数です"
# "4は偶数です"
# "5は奇数です"

greetings = ["こんにちは","おはよう","さよなら"]
greetings.each_with_index do |greeting,i|
  puts "#{i+1}"+":"+ "#{greeting}"
end

#実行結果
#1:こんにちは
#2:おはよう
#3:さよなら

greetings = ["こんにちは","おはよう","さよなら"]
greetings.each_with_index do |greeting|
  puts  "#{greeting}"
end

#こんにちは
#おはよう
#さよなら

for i in 0..10 do
  puts i 
end

animals = { :dog => "犬", :cat => "猫", :monkey => "猿" }

for key,value in animals
  puts "#{value}を英語でいうと#{key}です"
end

#実行結果
#dog
# 犬
# cat
# 猫
# monkey
# 猿

5.times do
  puts "Hello"
end

#実行結果
#"Hello"
# "Hello"
# "Hello"
# "Hello"
# "Hello"

5.times do |i|
  puts "#{i+1}回目の:Hello"
end

#実行結果
# 1回目の:Hello
# 2回目の:Hello
# 3回目の:Hello
# 4回目の:Hello
# 5回目の:Hello

i = 1
while i < 101 
  if i.even?
  puts "#{i}は偶数です"
  else
    puts "#{i}は奇数です"
  end

  i +=1  # 自己代入
end

i = 1
while i < 101
  puts i
  break if i == 20
  i +=1  # 自己代入
end

nums = [1,2,3,4,5,6]
nums.each do |num|
  if num.odd?
   next
  end
   p num
end

実行結果
# 2
# 4
# 6

num=[1,3,5]
p num.all?(&:odd?)

実行結果
true