June 2026
Intermediate
804 pages
8h 21m
Japanese
Content preview from 入門 Python 3 第3版
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5章バイト列
ちょビット具合が悪いもので…
—— 病欠の電話をかけてきたあるバイト
Python 3は、0から255までの値を取る8ビット整数のシーケンスとしてデータ型を2種類導入した。
- 8ビット値のイミュータブルなシーケンス：
bytes - 8ビット値のミュータブルなシーケンス：
bytearray
本章ではバイト列（bytesとbytearray）の基礎を解説する。また、「20章 ファイル」ではバイナリファイル形式などの実用的な用途について、より詳しく扱う。バイナリデータを文字列ほど頻繁に扱うことはおそらくない。
bytesとbytearrayの詳細はPythonの公式ドキュメントに記載されている。本章では、その中でも特に一般的で有用な部分に絞って説明する。
バイト列と文字列の違いは次のように考えるとよい。
- バイト列は、同じ大きさのビーズがワイヤーに連なっているもの。
- 文字列は、さまざまな大きさの飾りが付いたチャームブレスレットのようなもの。
5.1 bytes型
bytesは文字列と同様にイミュータブルである。bytes型の値を作成した後は、その内容の追加、挿入、変更ができない。
5.1.1 クォートによる作成
リテラルのbytesオブジェクトは、文字列と同様にクォートで囲んで作成するが、先頭のクォートの直前にbを付ける。バイト列内の各バイトは、ASCII文字または2桁の16進数リテラルで指定する。
>>> b1 = b"ABC\x01\x02\x03\x41\x42\x43" >>> b1 b'ABC\x01\x02\x03ABC' >>> b2 = b"abc\x01\x02\x03\x61\x62\x63" >>> b2 b'abc\x01\x02\x03abc' ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.