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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135
9
章
ポインタ
ポインタはデータオブジェクトまたは関数を指す。ポインタには、「参照呼び出し」関数
の定義やリンク付きリストや木などの動的データ構造の実装など多くの用途がある。
大量のデータを管理する効率的な方法が、データそのものではなくデータへのポインタ
の操作ということがしばしばある。例えば、多数の大きなレコードをソートする場合、レ
コードそのものをメモリ内で移動するよりもレコードへのポインタのリストをソートしたほ
うがより効率的なことが多い。同様に、関数に大きなレコードを渡す必要があり、関数が
内容を変更しない場合、レコード内容を渡すよりもレコードへのポインタを渡す方がはるか
に経済的だ。
9.1
ポインタを宣言
ポインタはオブジェクトまたは関数のアドレスと型の両方を表す。オブジェクトまたは
関数が型
T
を持てば、それへのポインタは型
T
へのポインタ型を持つ。
var
が
float
変数な
ら、値がその
float
変数のアドレスである式
&var
が
float
へのポインタ型、C表記では型
float*
を持つ。任意の型
T
へのポインタは、
T
ポインタとも呼ばれる。
&var
のアドレス演算
子は
float
ポインタを値とする。
var
はメモリを動き回らないから、式
&var
は定数ポインタだ。Cではポインタ型の変数も
定義できる。ポインタ変数は他のオブジェクトまたは関数のアドレスを格納する。配列や
関数へのポインタを少し後で述べる。配列以外のオブジェクトへのポインタの宣言は次の
構文で行う。
type
* [
type-qualifier-list ...
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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.