Develop
2013.10.31 16:51
[ios] Random Thoughts: Rand() vs. arc4random()
Views 68050 Comment 0
랜덤함수 사용시..
iOS
There are several built-in randomizers on the iPhone, and most people's first thought is to use rand() after seeding it by calling
srandom(time(NULL));
But... rand() is really not a very good PRNG. random() is a little better, but still less then ideal. Fortunately, these are not the only ones available on the iPhone. Personally, I like arc4random() because it's a decent pseudo-random algorithm and has twice the range or rand().
On the iPhone, RAND_MAX is 0x7fffffff (2147483647), while arc4random() will return a maximum value of 0x100000000 (4294967296), giving much more precision. You also don't need to seed arc4random(), as the first call to it automatically seeds it.
결론은 arc4random() 을 사용하자.
[출처] http://iphonedevelopment.blogspot.com/2008/10/random-thoughts-rand-vs-arc4random.html
No. | Category | Subject | Author | Date | Views |
---|---|---|---|---|---|
381 | System/OS | [linux] Proftpd 설치 가이드 | hooni | 2003.04.23 | 13028 |
380 | System/OS | [linux] ProFTPD 타임아웃 설정 | hooni | 2003.04.23 | 12851 |
379 | System/OS | [linux] resolv.con 초기화 되는 문제 | hooni | 2014.04.05 | 4624 |
378 | System/OS | [linux] root 전환시 패스워드 없이 su 사용하기 | hooni | 2013.12.22 | 12688 |
377 | System/OS | [linux] root도 삭제하지 못하는 파일 속성 | hooni | 2003.04.23 | 12412 |
376 | System/OS | [linux] sendmail 설정/사용 | hooni | 2003.04.23 | 14574 |
375 | System/OS | [linux] split 명령어 | hooni | 2014.03.11 | 4307 |
374 | System/OS | [linux] SSH에 대한 기본 설명과 설치/설정 | hooni | 2013.04.23 | 10499 |
373 | System/OS | [linux] ssh에서 원격 파일 전송하기.. | hooni | 2013.04.23 | 14161 |
372 | Develop | [linux] tar 명령어 뽀개기.. ㅋㅋ | hooni | 2003.04.23 | 7671 |
371 | System/OS | [linux] The Ultimate Wget Download Guide With 15 Awesome Examples | hooni | 2020.05.26 | 810 |
370 | System/OS | [linux] vi 편집기 간단한 명령과 환경설정 | hooni | 2003.04.23 | 11360 |