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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17.10
日付と時刻
323
れる、表17-22に示す4つの動的メモリ関数で行うことができる。これらの関数の使用の詳
細は12章で述べた。
表17-22 動的メモリ管理関数
目的 関数
メモリブロックを割り当てる
malloc()
メモリブロックを割り当てナルバイトで埋める
calloc()
割り当てたメモリブロックのサイズを変更する
realloc()
メモリブロックを解放する
free()
17.10
日付と時刻
ヘッダtime.hは、現在の日付と時刻の取得、プロセスの実行時間取得、日付と時刻情報
の変換、およびその出力用フォーマットを行う標準ライブラリ関数を宣言する。主たる関数
は型
time_t
の算術値形式で現在のカレンダー時刻を返す
time()
だ。これは通常、紀元と呼
ばれる過去の一時点からの経過秒数で示される。Unixの紀元はUTC（以前はグリニッジ標
準時GMTと呼ばれた協定世界時）1970年1月1日00:00:00だ。
型
time_t
のカレンダー時刻値を文字列または型
struct tm
の構造体に変換する標準関
数もある。この構造体は秒、分、時、日、月、年、曜日、年通算日、夏時間フ
ラグ（18章
gmtime()
参照）の型
int
メンバを持つ。表17-23はすべての日付と時刻関数を示す。
表17-23 日付時刻関数
目的 関数
使用CPU時間量を求める
clock()
現在のカレンダー時刻を求める
time()
2つのカレンダー時刻の差をとる
difftime()
カレンダー時刻を
struct tm
に変換する
gmtime() ...
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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.