Algorithm to convert int to 6 character alphanumeric string

Question

I have an ID field that automatically increments by 1 when a new record is added. Rather than use the numeric ID as is, I would like to convert it to a 6 character string made up of 0-9A-Z (no lowercase letters) with the following format:

A00000

The numbers should increment from 0-9 then A-Z.

Examples

If I were to encode the number 7 for example, it should return:

A00007

If I encode the number 13 it should return:

A0000D

If I encode the number 36 it should return:

A00010

Hopefully this makes sense. Any help would be greatly appreciated.

@phoog I've tried some base 36 encoding with some luck but I was curious to see if there's a better solution out there. And yes, that should have been a 36. Typo fixed. — Jason Towne, Dec 04 '12 at 23:50
I wrote some code to do that kind of stuff in answer to http://stackoverflow.com/questions/8885582/c-sharp-shorten-int-into-case-sensitive-code/8886171#8886171 — Keith Nicholas, Dec 04 '12 at 23:52
Suggestion: Add 604661760 to the integer value ( = 10 * 36 ^ 5 ), then encode in base 36. — phoog, Dec 04 '12 at 23:52
@phoog That's brilliant! If you write up your comment as an answer I'll be happy to upvote and accept. — Jason Towne, Dec 04 '12 at 23:57

phoog · Accepted Answer · 2012-12-05T14:30:50.820

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Suggestion: Add 604661760 to the integer value. That's the base-10 value of A00000, interpreted as a base-36 number ( = 10 * 36 ^ 5 ).

Then encode the result in base 36.

Depending on your data range, you might want to promote the int to a long before adding 604661760.

edited Dec 05 '12 at 14:30

answered Dec 05 '12 at 00:00

phoog

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Good idea with your `int` vs. `long` suggestion. Thanks again. – Jason Towne Dec 05 '12 at 00:10

score 1 · Answer 2 · answered Dec 04 '12 at 23:52

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What you have here is conversion from a base 10 number to a base 36 number. Here's an algorithm for conversion from base 10 to base K. Modify it to suit your needs:

http://www.cs.umd.edu/class/sum2003/cmsc311/Notes/Data/toBaseK.html

answered Dec 04 '12 at 23:52

System Down

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Algorithm to convert int to 6 character alphanumeric string

2 Answers2