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
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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.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.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.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.
19.6
最適化
673
#define printerror(x) fputs("x\n", stderr)
古い「伝統的」Cでは、このマクロは意図通りに働くだろうが、ISO標準Cでは、文字「x」
と改行文字を表示する。この行に対して
-Wtraditional
は次のような警告を発する。
file
:
line
:
column
: warning: macro argument "x" would be stringified in traditional C
19.6
最適化
GCCでは生成した実行プログラムをより速く、より小さくするために多くの技法を適用
できる。これらの技法はいずれも書かれたCプログラムとコンピュータが読むマシンコード
との間の「一語一語」対応を簡約化していく。結果的にデバッグがより困難になるので、通
常は最適化なしでプログラムのテストとデバッグが終わってから適用される。
最適化オプシ
ョンには2種類ある。異なるソースファイルに関しても共通の位置で同一の
定数をコンパイラに置かせるような
-fmerge-constants
のように
-f
から始まるオプション
で適用する個別最適化技法と、
-O
オプション（
-O0
,
-O1
,
-O2
,
-O3
）を用いて累積的に複数の
技法を一度に適用する最適化レベルを設定する方法がある。
19.6.1
-O
レベル
各
-O
オプションは複数の最適化技法を表す。
-O
最適化は累積的で、
-O2
が
-O1
の全最適
化を含み、
-O3
が
-O2
を含む。各レベルとそれらが表す
-f
最適化オプショ
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
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.