Sean M. Burke


Number::Latin -- convert to/from the number system "a,b,...z,aa,ab..."


  use Number::Latin;
  print join(' ', map int2latin($_), 1 .. 30), "\n";
   # Prints:
   #  a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad


Some applications, notably the numbering of points in outlines, use a scheme that starts with the letter "a", goes to "z", and then starts over with "aa" thru "az", then "ba", and so on. (The W3C refers to this numbering system as "lower-latin"/"upper-latin" or "lower alpha"/"upper alpha", in discussions of HTML/CSS options for rendering of list elements (OL/LI).)

This module provides functions that deal with that numbering system, converting between it and integer values.


This module exports four functions, int2latin, int2Latin, int2LATIN, and latin2int:

$latin = int2latin( INTEGER )

This returns the INTEGERth item in the sequence ('a' .. 'z', 'aa', 'ab', etc). For example, int2latin(1) is "a", int2latin(2) is "b", int2latin(26) is "z", int2latin(30) is "ad", and so for any nonzero integer.

$latin = int2Latin( INTEGER )

This is just like int2latin, except that the return value is has an initial capital. E.g., int2Latin(30) is "Ad".

$latin = int2LATIN( INTEGER )

This is just like int2latin, except that the return value is in all uppercase. E.g., int2LATIN(30) is "AD".

$latin = latin2int( INTEGER )

This converts back from latin number notation (regardless of capitalization!) to an integer value. E.g., latin2int("ad") is 30.


The latin numbering system is not to be confused with Roman numerals, in spite of their names.

The latin numbering system isn't a normal base-N number system (thus making this module necessary), as evidenced by the fact that the item after "z" is "aa". If you considered this to be a base-26 numbering system (running from a-z for 0-25), then after "z" would be "ba"; if you considered it a base-27 numbering system (running from a-z for 1-26), then after "z" would be "a" followed by some sort of placeholder zero. But it's neither.

I vaguely remember reading, years ago, of some languages (in New Guinea?) with count-number systems that work like the latin number system -- i.e., where either the number after "nine" is "one-MULT one", or the number after "ten" is "one-MULT one". However, I haven't been able to find a reference for exactly what language(s) those were number system; I welcome email on the subject.


Copyright (c) 1997- by Abigail, and 2001- Sean M. Burke. All rights reserved.

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.




Initial implementation in a comp.lang.perl.misc post by Abigail ( in 1997. Documentation, further doings, and current maintenance by Sean M. Burke,