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ruby while、for、loop、break、nextについて

Posted at

#while

 i = 0
 while i < 10 do
     puts "#{i}: hello" 
     i += 1
 end

※ 「i = i + 1」は「 i += 1 」と同様の意味

times

  • timesは数字オブジェクトのメソッド
10.times do |i|
puts "#{i}:hello"
end
  • do~endの中で繰り返したい処理を繰り返す
  • do の後で|i|を定義することでwhileの時と同じように何回ループしているかが分かる

###上記のtimesは1行で書くことが出来る

10.times { |i|puts "10#{i}:hello" }

for文

  • doは省略出来る
 for i in 18..20 do
     p i
 end
 for color in ["red", "blue"] do
     p color
 end

 for name,score in {aratomai: 200, Mikkey: 500} do
     puts "#{name}: #{score}"
 end

実行結果:

  • 18
  • 19
  • 20
  • "red"
  • "blue"
  • aratomai: 200
  • Mikkey: 500

eachメソッドへの書き換え

 (18..20).each do |i|
     p i
 end
 ["red", "blue"].each do |color|
     p color
 end
 {aratomai: 200, Mikkey: 500}.each do |name, score|
     puts "#{name}: #{score}"
 end

実行結果:
上記と同じ

loop

  • breakしない限り永久ループ
i = 0
 loop do
     p i
     i += 1
     end

breakとnextについて

  • iが5になった時に処理が終わる
10.times do |i|
    if i == 5
        break
    end
    p i
end

実行結果:
0
1
2
3
4

  • iが5の時だけ処理をスキップする
10.times do |i|
    if i == 5
        next
    end
    p i
end

実行結果:
0
1
2
3
4
6
7
8
9

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