In Unicode, why are there two representations for the Arabic digits?

Question

I was reading the specification of Unicode @ Wikipedia (Arabic Unicode) and I see that each of the Arabic digits has 2 Unicode code points. For example 1 is defined as U+066

Answer 1

In general you should not hard-code such info in your application.

• On Windows you can use GetLocaleInfo with LOCALE_SNATIVEDIGITS.
• On Mac CFNumberFormatterCopyProperty with kCFNumberFormatterZeroSymbol.
• Or use something like ICU.

There are Arabic countries that don't use the Arabic-Indic digits by default. So there is no direct mapping saying Arabic -> Arabic-Indic digits.

And the user might have changed the defaults in the Control Panel anyway.