Geography::Countries is a Perl module with 2-letter, 3-letter, and numerical codes for countries.
$country = country 'DE'; # 'Germany'
@list = country 666; # ('PM', 'SPM', 666,
# 'Saint Pierre and Miquelon', 1)
This module maps country names, and their 2-letter, 3-letter and numerical codes, as defined by the ISO-3166 maintenance agency , and defined by the UNSD.
The country subroutine.
This subroutine is exported by default. It takes a 2-letter, 3-letter or numerical code, or a country name as argument. In scalar context, it will return the country name, in list context, it will return a list consisting of the 2-letter code, the 3-letter code, the numerical code, the country name, and a flag, which is explained below. Note that not all countries have all 3 codes; if a code is unknown, the undefined value is returned.
There are 3 categories of countries. The largest category are the current countries. Then there is a small set of countries that no longer exist. The final set consists of areas consisting of multiple countries, like Africa. No 2-letter or 3-letter codes are available for the second two sets. (ISO 3166-3  defines 4 letter codes for the set of countries that no longer exist, but the author of this module was unable to get her hands on that standard.) By default, country only returns countries from the first set, but this can be changed by giving country an optional second argument.
The module optionally exports the constants CNT_F_REGULAR, CNT_F_OLD, CNT_F_REGION and CNT_F_ANY. These constants can also be important all at once by using the tag :FLAGS.
CNT_F_ANY is just the binary or of the three other flags. The second argument of country should be the binary or of a subset of the flags CNT_F_REGULAR, CNT_F_OLD, and CNT_F_REGION - if no, or a false, second argument is given, CNT_F_REGULAR is assumed. If CNT_F_REGULAR is set, regular (current) countries will be returned; if CNT_F_OLD is set, old, no longer existing, countries will be returned, while CNT_F_REGION is used in case a region (not necessarely) a country might be returned. If country is used in list context, the fifth returned element is one of CNT_F_REGULAR, CNT_F_OLD and CNT_F_REGION, indicating whether the result is a regular country, an old country, or a region.
In list context, country returns a 5 element list. To avoid having to remember which element is in which index, the constants CNT_I_CODE2, CNT_I_CODE3, CNT_I_NUMCODE, CNT_I_COUNTRY and CNT_I_FLAG can be imported. Those constants contain the indices of the 2-letter code, the 3-letter code, the numerical code, the country, and the flag explained above, respectively. All index constants can be imported by using the :INDICES tag.
The code2, code3, numcode and countries routines.
All known 2-letter codes, 3-letter codes, numerical codes and country names can be returned by the routines code2, code3, numcode and countries. None of these methods is exported by default; all need to be imported if one wants to use them. The tag :LISTS imports them all. In scalar context, the number of known codes or countries is returned.