Re: How to generate a random number?

[Liu Tao <debian@0451.com>]

On Friday 05 October 2001 01:36, Jeffrey W. Baker wrote:
> On Thu, 4 Oct 2001, Alan Shutko wrote:
> > "Jeffrey W. Baker" <jwbaker@acm.org> writes:
> > > That is an extraordinarily bad idea.  Any person will be able to guess
> > > the sequence of random numbers simply by guessing the time at which
> > > your program was started.
> >
> > And the impact of this depends on what the program is used for.  If
> > you're seeding the RNG for a crypto program, yes, this is bad.  If
> > you're seeding the RNG for a random sig generator, who cares?  Why use
> > up entropy for programs which don't need it?
>
> Right, but those conditions weren't explained in the original advice to
> use srand(time()).  When someone asks "How do I generate a random number"
> I think it's a lot safer to advise /dev/random than time().
>
> In either case I would hope that critical software isn't being written by
> people who don't even know how to generate random numbers.
>
> -jwb

Thanks for all replys.
I have known the methords to generate random numbers.
/dev/random is more safe , but time() is safe enough to me.
In fact  I  only need some different numbers for children's  mahts.

Liu Tao