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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4.1
算術型の変換
51
複素数が符号なし整数型に変換されるとき、虚数部は最初に捨てられる。次に結果の浮
動小数点値が既に述べたように変換される。例を示す。
#include <limits.h> // UINT_MAX
のようなマクロを定義
#include <complex.h> //
虚数定数
I
のようなマクロを定義
unsigned int n = 0;
float _Complex z = -1.7 + 2.0 * I;
n = z; //
この場合、効果は
n = -1;
と同じ。
n
の結果値は
UINT_MAX
z
の虚部は切り捨てられ、実浮動小数点値−1.7が残る。そして浮動小数点数の小数以下
も切り捨てられる。残った整数値−1は、
UINT_MAX
＋1を足して
unsigned int
に変換され、
最終的に
n
への代入値は
UINT_MAX
と等しくなる。
4.1.5.3
符号付き整数型への変換
例えば、型
long
または
unsigned int
から型
int
への変換のように、符号の有無を問わず
整数型から異なる符号付き整数型への変換では、値が変換後の型の値範囲を超える問題が
起こる。そのような符号付き整数型への変換オーバーフローの結果は、符号なし整数型へ
の変換とは異なり、実装に任される。
ほとんどのコンパイラは、元の値の2進表現での最高位ビットを捨てて、下位ビットを新
たな型で解釈する。次の例からわかるように、この変換戦略では、
unsigned int
の既存ビッ
トパターンが符号付き
int
値として解釈される。
#include ...
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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.