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.
15.5
行番号を定義する
267
defined
identifier
defined (
identifier
)
これらのプリプロセッサ式は、指定識別子がマクロ名、すなわち
#define
指令で定義さ
れ定義が
#undef
指令で取り消されていないなら、値1を持つ。その他の識別子については、
値0となる。
#ifdef
や
#ifndef
指令に比べて、
defined
演算には値をより大きなプリプロセッサ式の中
で使えるという利点がある。例を挙げる。
#if defined(__unix__) && defined(__GNUC__)
/* ... */
#endif
ほとんどのコンパイラがこの例で使用するような定義済みマクロを提供しており、それ
を用いてターゲットシステムとコンパイラを識別している。したがって、Unixシステム
では、マクロ
__unix__
が通常定義されており、コンパイラがGCCならマクロ
__GNUC__
が
定義されている。
同様に、Windowsの Microsoft Visual Cコンパイラはマクロ
_WIN32
と
_MSC_VER
を定義する。
15.4.3
#ifdef
と
#ifndef
指令
#ifdef
と
#ifndef
指令で指定したマクロが定義されているかどうかを調べられる。構文
は次の通り。
#ifdef
identifier
#ifndef
identifier
これらは次の
#if
指令と等価だ。
#if defined
identifier
#if ! defined
identifier
#ifndef
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.