【初心者向け】Ruby のまずいコード 25 本 Advent Calendar 2021

1 participant

25 subscriber

15 likes

Category：Programming language

Creator：

Ruby の初心者が書いてしまいがちなまずいコードとその改善例を集めました。
「まずい」の意味は，バグがあってまずい場合だけでなく，動作は正常だけど必要以上に複雑なコードや，効率の悪いコードも含みます。
なお，「まずい」として挙げたコードでも，条件次第ではそれでよい場合がありますし，まずさの度合いもさまざまです。

How to join the calendar

You can join the calendar by selecting an available date and registering the URL of the article you wish to link to. If a slot is available, you can go back to a past date to join!

Series 1

Sunday	Monday	Tuesday	Wednesday	Thursday	Friday	Saturday
28	29	30	@scivola 【Ruby のまずいコード】除算の落とし穴 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】二乗和 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】文字列を文字の配列にする Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】leet Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use
@scivola 【Ruby のまずいコード】次の整数 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】階乗 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】HTML エスケープ Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】ハッシュのキーのシンボル化 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】Pathname で与えられたディレクトリーでの glob Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】正規表現で特定の文字を囲む Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】数字を削除 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use
@scivola 【Ruby のまずいコード】ファイル書き出し Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】ID として可能な文字列か判定 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】回文素数を表示 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】文字列の先頭から n 文字を取得する Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】最初の n 個の素数 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】リストにある文字列を抽出 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】数値が全て一定範囲に収まっているか Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use
@scivola 【Ruby のまずいコード】2022 年の日曜日はいくつ？ Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】シーザー暗号 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】文字列連結 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】文字列を文字種で分割 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】素数判定 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】引数の扱い Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】漢字を数える Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use

@scivola
【Ruby のまずいコード】除算の落とし穴
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】二乗和
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】文字列を文字の配列にする
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】leet
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】次の整数
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】階乗
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】HTML エスケープ
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】ハッシュのキーのシンボル化
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】Pathname で与えられたディレクトリーでの glob
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】正規表現で特定の文字を囲む
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】数字を削除
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】ファイル書き出し
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】ID として可能な文字列か判定
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】回文素数を表示
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】文字列の先頭から n 文字を取得する
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】最初の n 個の素数
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】リストにある文字列を抽出
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】数値が全て一定範囲に収まっているか
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】2022 年の日曜日はいくつ？
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】シーザー暗号
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】文字列連結
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】文字列を文字種で分割
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】素数判定
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】引数の扱い
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】漢字を数える
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use

Sunday	Monday	Tuesday	Wednesday	Thursday	Friday	Saturday
28	29	30	@scivola 【Ruby のまずいコード】除算の落とし穴 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】二乗和 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】文字列を文字の配列にする Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】leet Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use
@scivola 【Ruby のまずいコード】次の整数 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】階乗 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】HTML エスケープ Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】ハッシュのキーのシンボル化 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】Pathname で与えられたディレクトリーでの glob Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】正規表現で特定の文字を囲む Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】数字を削除 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use
@scivola 【Ruby のまずいコード】ファイル書き出し Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】ID として可能な文字列か判定 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】回文素数を表示 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】文字列の先頭から n 文字を取得する Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】最初の n 個の素数 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】リストにある文字列を抽出 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】数値が全て一定範囲に収まっているか Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use
@scivola 【Ruby のまずいコード】2022 年の日曜日はいくつ？ Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】シーザー暗号 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】文字列連結 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】文字列を文字種で分割 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】素数判定 Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】引数の扱い Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use	@scivola 【Ruby のまずいコード】漢字を数える Overwrite Title URL You can post either your article on Qiita or your blog post. About reserved posting If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day. About posting period Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.) When you participate, we will assume that you have agreed to the terms of use

@scivola
【Ruby のまずいコード】除算の落とし穴
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】二乗和
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】文字列を文字の配列にする
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】leet
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】次の整数
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】階乗
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】HTML エスケープ
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】ハッシュのキーのシンボル化
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】Pathname で与えられたディレクトリーでの glob
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】正規表現で特定の文字を囲む
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】数字を削除
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】ファイル書き出し
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】ID として可能な文字列か判定
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】回文素数を表示
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】文字列の先頭から n 文字を取得する
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】最初の n 個の素数
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】リストにある文字列を抽出
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】数値が全て一定範囲に収まっているか
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】2022 年の日曜日はいくつ？
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】シーザー暗号
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】文字列連結
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】文字列を文字種で分割
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】素数判定
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】引数の扱い
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use
@scivola
【Ruby のまずいコード】漢字を数える
Overwrite
Title
URL
You can post either your article on Qiita or your blog post.
About reserved posting
If you register a secret article by the day before the same day, it will be automatically published around 7:00 on the same day.
About posting period
Only articles submitted after November 1 of the year can be registered. (Secret articles can be registered anytime articles are posted.)
When you participate, we will assume that you have agreed to the terms of use

You can increase the number of series when Calendar 1 is filled with more than 10 articles.

【初心者向け】Ruby のまずいコード 25 本 Advent Calendar 2021

edit_calendarHow to join the calendar

Series 1

How to join the calendar