This looks good. THank you. Going to test it out. Was thinking currenttimestamp could make it unique, but converting it to non-obvious random-looking code was stumping me. thanks.
On Oct 14, 2010, at 10:53 AM, Robert Shubert wrote: > Try this out: > > <@! start with epoch> > <@ASSIGN secs <@TSTOSECS <@CURRENTTIMESTAMP>>> > > <@! add salt> > <@ASSIGN secs "<@RANDOM low=1 high=9>@@secs<@RANDOM low=1 high=9>"> > > <@! convert to base 26> > <@WHILE expr="@@secs > 26"> > > <@! shift to ascii for capitals 65-90 convert to char and build code> > <@IF "<@CURROW>%2 = 0"> > <@ASSIGN code '<@CHAR <@CALC "abs(@@secs % 26) + 65">>@@code'> > <@ELSE> > <@ASSIGN code '@@code<@CHAR <@CALC "abs(@@secs % 26) + 65">>'> > </@IF> > > <@! shift place for base conversion> > <@ASSIGN secs <@CALC "@@secs / 26" precision=0>> > > </@WHILE> > > Final Code: @@code > > DISCLAIMER: It is possible to create the same code if this routine is run > multiple times in the same second. Add a <@SLEEP 1000> to prevent this. Also, > there is an abs() in there because doing modulo on large values produces a > negative value. This is incorrect behavior on Witango's part and something > that I'll need to fix in the server. I do not think it produces a collision > problem in this routine, but it may. It is likely tied to small floating > point variable used in the routine. Oh, and there is also a rounding error > that I didn't work out, but again, it only changed some shift points (26^1 > place increases at unit=13 rather than unit=0). This can removed by > floor()ing the base conversion shift in the final @CALC. Again, I do not > believe that this causes a collision situation. Also, this routine can > occasionally create a 7 character code. You may need to check for and ignore > these if you want them all to 8 characters (This may be able to be eliminated > by increasing the LOW value in the first @RANDOM) Lastly, I don't guarantee > this routine. I just whipped it up as a mental exercise, so you may want to > test it out some (see if you get a collision over a few million iterations), > or show it to someone who is good with algorithms or cryptography. > > Robert > > -----Original Message----- > From: Roland Dumas [mailto:radu...@mac.com] > Sent: Thursday, October 14, 2010 11:42 AM > To: Witango-Talk@witango.com > Subject: Witango-Talk: generating unique codes > > > looking for method to create unique and non-obvious n-digit codes to be used > as discount codes. > Should be short enough to use as consumer codes (8 digit?), and probably be > something simply to enter, such as an all caps, and not have an easily > discoverable pattern. > > I want to generate unique codes and not have to check the history to see if a > code has been used before. > > Suggestions? > > > > > > ---------------------------------------- > > To unsubscribe from this list, please send an email to lists...@witango.com > with "unsubscribe witango-talk" in the body. > > > > ---------------------------------------- > > To unsubscribe from this list, please send an email to lists...@witango.com > with "unsubscribe witango-talk" in the body. > ---------------------------------------- To unsubscribe from this list, please send an email to lists...@witango.com with "unsubscribe witango-talk" in the body.
