【戻る】 【進む】   目次        36. 組み込みクラス - Hash

# ハッシュ（Hash）

```インデックス参照、代入
receipt = {"apple" => 250, "banana" => 170, "cranberry" => 200 }
receipt["banana"] #=> 170

receipt["banana"] = 180
receipt["banana"] #=> 180

receipt = {"apple" => 250, "banana" => 170, "cranberry" => 200 }
receipt.delete("banana")  #=> bananaを削除
receipt                   #=> {"apple"=>250, "cranberry"=>200 }

receipt = {"apple" => 250, "banana" => 170, "cranberry" => 200 }
receipt.delete_if { |x, v| x == "apple" && v >= 250 }
#=> appleの値が250以上だったら削除
receipt                   #=> {"banana" => 170, "cranberry"=>200 }
each
receipt = {"apple" => 250, "banana" => 170, "cranberry" => 200 }
receipt.each do |x, v|
print x, "=>", v, "\n"
end

receipt = {"apple" => 250, "banana" => 170, "cranberry" => 200 }
receipt.keys   #=> ["apple", "banana", "cranberry"]
receipt.values #=> [250, 170, 200]
size, empty?

{"apple"=>250, "banana"=>170}.size  #=> 2
p ({}.empty?)        #=> true
p ({""=>""}.empty?)  #=> false

```

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