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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262
15
章 プリプロセッサ指令
#define printDBL(exp) printf(#exp " = %f ", exp)
printDBL(4 * atan(1.0)); // atan()
は
math.h
で宣言される
最後の行のマクロ呼び出しは次の文になる。
printf("4 * atan(1.0)" " = %f ", 4 * atan(1.0));
コンパイラが連続する文字列リテラルを連結するので、このコードは次の行と等しい。
printf("4 * atan(1.0) = %f ", 4 * atan(1.0));
この文は次のコンソール出力を生成する。
4 * atan(1.0) = 3.141593
次の例での
showArgs
マクロの呼び出しは、
#
演算子がマクロ引数の空白文字、二重引用
符、バックスラッシュをどう変更するかを示す。
#define showArgs(...) puts(#__VA_ARGS__)
showA
rgs(one\n, "2\n", three);
プリプロセッサはこのマクロを次のテキストに置き換える。
puts("one\n, \"2\\n\", three");
この文の出力は次になる。
one
, "2\n", three
15.2.2.3
トークン連結演算子
演算子
##
は2項演算子で任意のマクロの置換テキストで使える。左右のオペランドを一
緒にして1つのトークンにするので、トークン連結演算子と呼ばれる。結果のテキストがマ
クロ名を含むなら、プリプロセッサはそれをマクロ置換する。 ...
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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.