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Re: Seeding random() randomly
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Re: Seeding random() randomly


  • Subject: Re: Seeding random() randomly
  • From: Graham Cox <email@hidden>
  • Date: Fri, 27 May 2011 11:54:12 +1000

Weird.

Setting a breakpoint on srandom, setstate or srandomdev never triggers except for my own call of it. Using srandomdev doesn't change anything.

Switching to arc4random() gives me a varying random sequence, so that's a usable solution to my problem. But the behaviour with random() I'm seeing is mysterious.

--Graham




On 27/05/2011, at 11:15 AM, Dave Keck wrote:

>> I'm using random(), but every time I run my app I get the same sequence, despite having this code in my app delegate's -appDidFinishLaunching method. Clearly I'm not seeding it right, though I can't see why - I get a different value for seed every time. What gives?
>>
>>
>>        unsigned seed = (unsigned)([NSDate timeIntervalSinceReferenceDate] * 10000.0);
>>
>>        NSLog(@"launched, seed = %ld", seed );
>>        srandom( seed );
>
> I'm not sure what your problem is, but I believe arc4random() has
> superseded random() for a while now.

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References: 
 >Seeding random() randomly (From: Graham Cox <email@hidden>)
 >Re: Seeding random() randomly (From: Dave Keck <email@hidden>)

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