Just realized a serious problem with this approach: it will, due to its
nature, run very quickly towards +oo ... hence it is not proper to implement
as a computer program.
>-----Original Message-----
>From: Svensson, B.A.T. [mailto:[EMAIL PROTECTED]]
>Sent: Tuesday, January 23, 2001 9:10 PM
>To: [EMAIL PROTECTED]; [EMAIL PROTECTED]
>Subject: RE: [PHP-WIN] Random Code
>
>
>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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