November 2016
Beginner to intermediate
816 pages
19h 58m
Japanese
Content preview from Cクイックリファレンス 第2版
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10.4
ビットフィールド
167
10.4
ビットフィールド
構造体または共用体のメンバはビットフィールドでもよい。ビットフィールドは指定さ
れたビット幅の整数変数だ。小さなビットフィールドを続けて宣言すると、コンパイラが1
機械語に詰め込む。これは情報の小単位を非常にコンパクトに格納する。もちろん、個別
ビットをビット演算で扱えるが、ビットフィールドは他の構造体や共用体メンバと同じよう
にビット列を名前で扱えるという利点がある。
ビットフィールドの宣言は次の形式をとる。
type
[
member_name
] :
width
;
各部分の構文は次のようになる。
type
ビットフィールド値がどのように解釈されるか決める整数型。型は
_Bool
,
int
,
signed int
,
unsigned int
または実装定義の型でもよい。型修飾子も追加できる。
型
signed int
のビットフィールドは符号付きと解釈される。型が
unsigned int
の
ビットフィールドは符号なしと解釈される。型
int
のビットフィールドはコンパイ
ラによって符号付きとも符号なしともなる。
member_name
ビットフィールド名はオプション。名前なしで宣言すればアクセスする方法はな
い。名前なしビットフィールドは機械語において特定位置に続くビットフィールド
をアラインメント調整するパディングの役目のみ果たす。
width
ビットフィールドのビット数。幅は値が非負の定数式で、指定した型のビット幅以
下でなければならない。
名前なしビットフィ
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
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.