If one need to create multiple numbers per second (that is cal;culation time
is critical), then I would suggest, in accordance to my previous letter,
that one should pick a functions that is guaranteed to be constantly
growing, that is that the property "x1>x2 -> f(x1)>f(x2)" always will hold
true for the function f. If this is the case, then the f will be able to
produce input values for a mapping function that can be guaranteed to
produce unique numbers.
>-----Original Message-----
>From: Larry Forrister [mailto:[EMAIL PROTECTED]]
>Sent: Tuesday, January 23, 2001 7:26 PM
>To: [EMAIL PROTECTED]
>Subject: Re: [PHP-WIN] Random Code
>
>
>Do you mean W3E4-22ER would be valid? If so there would be 36^8
>(2,821,109,907,456) possible values.
>
>A truly random generator algorithm cannot guarantee uniqueness. I'm
>guessing what you want is to generate each possible value once in a
>pseudo-random order. Would just apparent randomness suffice?
>
>With what frequency do the values need to be generated? Once every few
>seconds/minutes or multiple times per second?
>~~LF
>
>
>Sigurd Magnusson wrote:
>
>> Whats the best way to make a completely random, unique code in the
>> format "ABCD-1234" where each of the 8 characters can be alphanumerc;
>> 0-9,A-Z... I thought about generating a 36^4 number, converting to to
>> base '36', and repeating the process. What's a good way to ensure the
>> code is not repeated, though?
>>
>> Siggy
>
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