【Ruby】 配列のおさらい

定義

human = ["yamada", "tanaka", "ueda"]
puts human #=> ["yamada", "tanaka", "ueda"]

ネスト

humans = [["yamada", "tanaka"], ["taro", "jiro"]]
puts humans[0] #=> ["yamada", "tanaka"]
puts humans[1][0] #=> "taro"

要素を結合した文字列を作成

human = ["yamada", "tanaka", "ueda"]
puts human.join(",") #=> "yamada,tanaka,ueda"

要素数を取得

human = ["yamada", "tanaka", "ueda"]
puts human.size #=> 3
puts human.length #=> 3

要素を追加

human = ["yamada", "tanaka", "ueda"]
human << "yabe"
puts human #=> ["yamada", "tanaka", "ueda", "yabe"]
puts human.push("jiro") #=> ["yamada", "tanaka", "ueda", "yabe", "jiro"]

# 先頭に追加
puts human.unshift("naoko") #=> ["naoko", "yamada", "tanaka", "ueda", "yabe", "jiro"]

末尾の要素を取り除いて返す

human = ["yamada", "tanaka", "ueda"]
puts human.pop #=> "ueda"
puts human #=> ["yamada", "tanaka"]

部分配列を取りだす

human = ["yamada", "tanaka", "ueda", "yabe", "jiro"]
puts human[0, 2] #=> ["yamada", "tanaka"]
puts human[1..3] #=> ["tanaka", "ueda", "yabe"]

クリア

human = ["yamada", "tanaka", "ueda", "yabe", "jiro"]
puts human.clear #=> []