by Michael S. Kaplan, published on 2005/01/24 00:04 -08:00, original URI: http://blogs.msdn.com/michkap/archive/2005/01/24/359347.aspx
Early last year, Raymond Chen talked about how Char.IsDigit matches more than just 0 through 9 and later last year I talked about Crossing the DIGITal divide. But in both cases the conversation is limited to digits, and not the wide world of numbers which includes a lot more than just different ways of saying 0123456789.
The distinction between digits and numbers in Unicode is an important one, since the formatting and parsing of numeric values is highly dependent on whether a number acts like the ASCII digits 0 - 9 or not.
Now the bulk of the modern number systems use the same Arabic-Indic system conventions to which software developers are accustomed, but others do exist, some of which are still see use today.
As an example people can relate to, most of us are aware of the Roman numeral system where there is no Zero and you sometimes have to use a lot of addition in subtraction in a deterministic manner (such that any time a smaller number comes before a larger one, the smaller one is subtracted; otherwise if they are the same value or the larger one comes first, it is added). Thus Ⅰ is one, Ⅲ is three, Ⅳ is 4, Ⅴ is 5, and so on. Although it is not used too much, it is still commonly seen in the credits of movies and television shows for the copyright date (e.g. MCMLXXXIX for 1989). Many people who are not used to Roman numerals breathed a sigh of relief at the year 2000 since MM is so much easier to read....
It is of note that the Roman Numerals are encoded in Unicode even though they can all be represented as existing letters. The primary reason for this is that there are character properties associated with each encoded character, and these properties are used by many implementations of Unicode to get actual work done. Therefore, the letter V (U+0056, LATIN CAPITAL LETTER V) has a General Category of Lu (Letter, Uppercase) while Ⅴ(U+2164, ROMAN NUMBERAL FIVE) has a general category of Nl (Letter, Number).
And yes, even that claim falls apart a little since the hexidecimal digits ABCDEF are not separately encoded for reasons of backwards compatibility with decades of existing practice on computers which is not the case with Roman numerals. Even the argument for having encoded the Roman numerals is a little specious since for the most part they have not been encoded and when they are the style never seems to be consistent typographically. Though YMMV since you may have better fonts than I do! Try "ⅯⅭⅯⅬⅩⅩⅩⅨ" for the test....
All of this goes to show that Unicode is a very complex standard. In the end, Unicode can always do what it needs to do without fear of the occasional contradiction, since there will always be some precedent with which to be consistent. :-)
Ethiopic numbers are based on a different alternative system, one that can really wreak havoc with a formatting/parsing architecture like that in Windows or the .NET Framework if you try to bring Ethiopic data in without writing code do the work (just like with Roman numerals). I'll talk about Ethiopic numbers another time....
Yet another system, the one I will talk about here, is that of Tamil numerals. It is an additive and positional system (unlike Roman numerals, there is no subtraction involved) that has no zero but includes characters for 10, 100, and 1000.
In the traditional system the number 3,782 would be represented as ௩௲௭௱௮௰௨ (literally Three-Thousand(s)-Seven-Hundread(s)-Eight-Ten(s)-Two, or மூன்று-ஆயிரத்து-எழு-நூற்று-எண்-பத்து-இரண்டு in Tamil).
At least since the early 1800s, however, usage of the Tamil numerals as digits has been more and more common. Thus the number 3,782 would often be represented as ௩௭௮௨ (literally 3782).
The following table gives a bunch of different numbers and how they are represented in both the older, more traditional style and in the "modern" style where they act as digits. Note that the table is treating U+0eb6 as TAMIL DIGIT ZERO even though it is not being added to Unicode until version 4.1. Up until now the ASCII DIGIT ZERO was used as needed, as I do in the table below for display purposes, and if you want to represent these numbers before Unicode 4.1 is released you should likely use U+0030 (DIGIT ZERO). The modern Tamil column using the LOCALE_SGROUPING setting of Tamil....
|Arabic-Indic Digit||old style Tamil||modern Tamil||old style Tamil code points||modern Tamil code points for number|
|0||(not available)||0||(not available)||0be6|
|11||௰௧||௧௧||0bf0 0be7||0be7 0be7|
|12||௰௨||௧௨||0bf0 0be8||0be7 0be8|
|13||௰௩||௧௩||0bf0 0be9||0be7 0be9|
|14||௰௪||௧௪||0bf0 0bea||0be7 0bea|
|15||௰௫||௧௫||0bf0 0beb||0be7 0beb|
|16||௰௬||௧௬||0bf0 0bec||0be7 0bec|
|17||௰௭||௧௭||0bf0 0bed||0be7 0bed|
|18||௰௮||௧௮||0bf0 0bee||0be7 0bee|
|19||௰௯||௧௯||0bf0 0bef||0be7 0bef|
|100||௱||௧00||0bf1||0be7 0be6 0be6|
|156||௱௫௰௬||௱௫௬||0bf1 0beb 0bf0 0bec||0be7 0beb 0bec|
|200||௨௱||௨00||0be8 0bf1||0be8 0be6 0be6|
|300||௩௱||௩00||0be9 0bf1||0be9 0be6 0be6|
|1,000||௲||௧,000||0bf2||0be7 0be6 0be6 0be6|
|1,001||௲௧||௧,00௧||0bf2 0BE7||0be7 0be6 0be6 0be7|
|1,040||௲௪௰||௧,0௪0||0bf2 0bea 0bf0||0be7 0be6 0bea 0be6|
|8,000||௮௲||௮,000||0bee 0bf2||0bee 0be6 0be6 0be6|
|10,000||௰௲||௧0,000||0bf0 0bf2||0be7 0be6 0be6 0be6 0be6|
|70,000||௭௰௲||௭0,000||0bed 0bf0 0bf2||0bed 0be6 0be6 0be6 0be6|
|90,000||௯௰௲||௯0,000||0bef 0bf0 0bf2||0bef 0be6 0be6 0be6 0be6|
|100,0001||௱௲||௧,00,000||0bf1 0bf2||0be7 0be6 0be6 0be6 0be6 0be6|
|800,000||௮௱௲||௮,00,000||0bee 0bf1 0bf2||0bee 0be6 0be6 0be6 0be6 0be6|
|1,000,0002||௰௱௲||௧0,00,000||0bf0 0bf1 0bf2||0be7 0be6 0be6 0be6 0be6 0be6 0be6|
|9,000,000||௯௰௱௲||௯0,00,000||0bef 0bf0 0bf1 0bf2||0bef 0be6 0be6 0be6 0be6 0be6 0be6|
|10,000,0003||௱௱௲||௧,00,00,000||0bf1 0bf1 0bf2||0be7 0be6 0be6 0be6 0be6 0be6 0be6 0be6|
|100,000,0004||௰௱௱௲||௧0,00,00,000||0bf0 0bf1 0bf1 0bf2||0be7 0be6 0be6 0be6 0be6 0be6 0be6 0be6 0be6|
|1,000,000,0005||௱௱௱௲||௧,00,00,00,000||0bf1 0bf1 0bf1 0bf2||0be7 0be6 0be6 0be6 0be6 0be6 0be6 0be6 0be6 0be6|
|10,000,000,0006||௲௱௱௲||௧0,00,00,00,000||0bf2 0bf1 0bf1 0bf2||0be7 0be6 0be6 0be6 0be6 0be6 0be6 0be6 0be6 0be6 0be6|
|100,000,000,0007||௰௲௱௱௲||௧,00,00,00,00,000||0bf1 0bf1 0bf2||0be7 0be6 0be6 0be6 0be6 0be6 0be6 0be6 0be6 0be6 0be6 0be6|
|1,000,000,000,0008||௱௲௱௱௲||௧0,00,00,00,00,000||0bf1 0bf2 0bf1 0bf1 0bf2||0be7 0be6 0be6 0be6 0be6 0be6 0be6 0be6 0be6 0be6 0be6 0be6 0be6|
|100,000,000,000,0009||௱௱௲௱௱௲||௧0,00,00,00,00,00,000||0bf1 0bf1 0bf2 0bf1 0bf1 0bf2||0be7 0be6 0be6 0be6 0be6 0be6 0be6 0be6 0be6 0be6 0be6 0be6 0be6 0be6 0be6|
1 - a.k.a. Lakh
2 - a.k.a. 10 Lakhs
3 - a.k.a. crore
4 - a.k.a. 10 crore
5 - a.k.a. 100 crore
6 - a.k.a. thousand crore
7 - a.k.a. 10 thousand crore
8 - a.k.a. lakh crore
9 - a.k.a. crore crore
Some examples of both types of usage:
Note that the traditional form is not currently handled by any code in either Windows or the .NET Framework, though it is sometimes seen in even modern contexts such as calendars. The system is not too complicated and figuring out the algorithm to parse or format with it seems like the sort of thing that would make an interesting Microsoft interview question. Though perhaps I will post some potential solutions another day....
Special thanks to Sivaraj Doddannan, Dr. N. Ganesan, and Working Group 02 of INFITT (of which they are both members) for helping to dig up the excellent resources for Tamil numbers. INFITT (International Forum for Information Technology in Tamil) is a liaison member of Unicode and has been instrumental in providing character addition and usage reports to help finish up the Tamil block in Unicode.
This post brought to you by "௧௨௩௪௫௬௭௮௯" (U+0be7 - U+0bef, a.k.a. TAMIL DIGIT ONE - TAMIL DIGIT NINE)
and they all welcome their new compadre U+0be6, which is coming soon to a Unicode near you!
# Bhakthan on Monday, January 24, 2005 7:06 AM:
# Andrew Quinn on Monday, January 24, 2005 8:15 AM:
# Michael Kaplan on Monday, January 24, 2005 8:29 AM:
# Dr. N. Ganesan on Monday, January 24, 2005 11:34 AM:
# Scott Hanselman on Tuesday, January 25, 2005 3:29 PM:
# Ambarish Sridharanarayanan on Saturday, January 29, 2005 9:59 PM:
# Michael Kaplan on Saturday, January 29, 2005 10:12 PM:
# Vatsan on Saturday, January 29, 2005 11:15 PM:
# Vatsan on Saturday, January 29, 2005 11:25 PM:
# Mani on Sunday, January 30, 2005 8:03 AM:
# Michael Kaplan on Sunday, January 30, 2005 8:51 AM:
# Paul on Monday, February 07, 2005 4:26 PM:
2006/08/10 Roman numerals are Latin script!
2005/02/01 Why that is positively Ethiopic!
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