Hi Jonny, On 12/26/22 22:50, Jonny Grant wrote:
Hi Alejandro
Please send also to my email.
Please find below a patch. 2022-12-26 Jonathan Grant <jg@xxxxxxxx> * man3/rand.3: Add example to rand.3 seed with time(NULL) From 2d4501354ea6c465173fe6c089dfbcc80393a644 Mon Sep 17 00:00:00 2001 From: Jonathan Grant <jg@xxxxxxxx> Date: Mon, 26 Dec 2022 21:48:17 +0000 Subject: [PATCH] add rand.3 example Signed-off-by: Jonathan Grant <jg@xxxxxxxx>
time(NULL) is not too good. If you call it several times per second, you'll find that it only changes the seed every second. There are better ways to produce a good seed.
However, I prefer suggesting arc4random() rather than workarounding rand(3) to get good results.
Florian, did you already merge arc4random() to glibc? Cheers, Alex
--- man3/rand.3 | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/man3/rand.3 b/man3/rand.3 index 572471749..c1542fb56 100644 --- a/man3/rand.3 +++ b/man3/rand.3 @@ -164,6 +164,20 @@ when good randomness is needed. .BR random (3) instead.) .SH EXAMPLES + +A possibly useful seed value would be by calling +.BR rand () +with the result of + +.BR time () +as that varies with every call + +.EX +srand((unsigned int)time(NULL)); +.EE +.in +.PP + POSIX.1-2001 gives the following example of an implementation of .BR rand () and
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