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[perl5.git] / lib / Locale / Country.pod

=head1 NAME

Locale::Country - ISO codes for country identification (ISO 3166)

=head1 SYNOPSIS

    use Locale::Country;
    
    $country = code2country('jp');        # $country gets 'Japan'
    $code    = country2code('Norway');    # $code gets 'no'
    
    @codes   = all_country_codes();
    @names   = all_country_names();
    
    # add "uk" as a pseudo country code for United Kingdom
    Locale::Country::_alias_code('uk' => 'gb');


=head1 DESCRIPTION

The C<Locale::Country> module provides access to the ISO
codes for identifying countries, as defined in ISO 3166.
You can either access the codes via the L<conversion routines>
(described below), or with the two functions which return lists
of all country codes or all country names.

There are three different code sets you can use for identifying
countries:

=over 4

=item B<alpha-2>

Two letter codes, such as 'tv' for Tuvalu.
This code set is identified with the symbol C<LOCALE_CODE_ALPHA_2>.

=item B<alpha-3>

Three letter codes, such as 'brb' for Barbados.
This code set is identified with the symbol C<LOCALE_CODE_ALPHA_3>.

=item B<numeric>

Numeric codes, such as 064 for Bhutan.
This code set is identified with the symbol C<LOCALE_CODE_NUMERIC>.

=back

All of the routines take an optional additional argument
which specifies the code set to use.
If not specified, it defaults to the two-letter codes.
This is partly for backwards compatibility (previous versions
of this module only supported the alpha-2 codes), and
partly because they are the most widely used codes.

The alpha-2 and alpha-3 codes are not case-dependent,
so you can use 'BO', 'Bo', 'bO' or 'bo' for Bolivia.
When a code is returned by one of the functions in
this module, it will always be lower-case.

As of version 2.00, Locale::Country supports variant
names for countries. So, for example, the country code for "United States"
is "us", so country2code('United States') returns 'us'.
Now the following will also return 'us':

    country2code('United States of America') 
    country2code('USA') 


=head1 CONVERSION ROUTINES

There are three conversion routines: C<code2country()>, C<country2code()>,
and C<country_code2code()>.

=over 4

=item code2country( CODE, [ CODESET ] )

This function takes a country code and returns a string
which contains the name of the country identified.
If the code is not a valid country code, as defined by ISO 3166,
then C<undef> will be returned:

    $country = code2country('fi');

=item country2code( STRING, [ CODESET ] )

This function takes a country name and returns the corresponding
country code, if such exists.
If the argument could not be identified as a country name,
then C<undef> will be returned:

    $code = country2code('Norway', LOCALE_CODE_ALPHA_3);
    # $code will now be 'nor'

The case of the country name is not important.
See the section L<KNOWN BUGS AND LIMITATIONS> below.

=item country_code2code( CODE, CODESET, CODESET )

This function takes a country code from one code set,
and returns the corresponding code from another code set.

    $alpha2 = country_code2code('fin',
		 LOCALE_CODE_ALPHA_3 => LOCALE_CODE_ALPHA_2);
    # $alpha2 will now be 'fi'

If the code passed is not a valid country code in
the first code set, or if there isn't a code for the
corresponding country in the second code set,
then C<undef> will be returned.

=back


=head1 QUERY ROUTINES

There are two function which can be used to obtain a list of all codes,
or all country names:

=over 4

=item C<all_country_codes( [ CODESET ] )>

Returns a list of all two-letter country codes.
The codes are guaranteed to be all lower-case,
and not in any particular order.

=item C<all_country_names( [ CODESET ] )>

Returns a list of all country names for which there is a corresponding
country code in the specified code set.
The names are capitalised, and not returned in any particular order.

Not all countries have alpha-3 and numeric codes -
some just have an alpha-2 code,
so you'll get a different number of countries
depending on which code set you specify.

=back


=head1 CODE ALIASING

This module supports a semi-private routine for specifying two letter
code aliases.

    Locale::Country::_alias_code( ALIAS => CODE [, CODESET ] )

This feature was added as a mechanism for handling
a "uk" code. The ISO standard says that the two-letter code for
"United Kingdom" is "gb", whereas domain names are all .uk.

By default the module does not understand "uk", since it is implementing
an ISO standard. If you would like 'uk' to work as the two-letter
code for United Kingdom, use the following:

    use Locale::Country;
    
    Locale::Country::_alias_code('uk' => 'gb');

With this code, both "uk" and "gb" are valid codes for United Kingdom,
with the reverse lookup returning "uk" rather than the usual "gb".


=head1 EXAMPLES

The following example illustrates use of the C<code2country()> function.
The user is prompted for a country code, and then told the corresponding
country name:

    $| = 1;   # turn off buffering
    
    print "Enter country code: ";
    chop($code = <STDIN>);
    $country = code2country($code, LOCALE_CODE_ALPHA_2);
    if (defined $country)
    {
        print "$code = $country\n";
    }
    else
    {
        print "'$code' is not a valid country code!\n";
    }

=head1 DOMAIN NAMES

Most top-level domain names are based on these codes,
but there are certain codes which aren't.
If you are using this module to identify country from hostname,
your best bet is to preprocess the country code.

For example, B<edu>, B<com>, B<gov> and friends would map to B<us>;
B<uk> would map to B<gb>. Any others?

=head1 KNOWN BUGS AND LIMITATIONS

=over 4

=item *

When using C<country2code()>, the country name must currently appear
exactly as it does in the source of the module. The module now supports
a small number of variants.

Possible extensions to this are: an interface for getting at the
list of variant names, and regular expression matches.

=item *

In the current implementation, all data is read in when the
module is loaded, and then held in memory.
A lazy implementation would be more memory friendly.

=item *

Support for country names in different languages.

=back

=head1 SEE ALSO

=over 4

=item Locale::Language

ISO two letter codes for identification of language (ISO 639).

=item Locale::Script

ISO codes for identification of scripts (ISO 15924).

=item Locale::Currency

ISO three letter codes for identification of currencies
and funds (ISO 4217).

=item ISO 3166

The ISO standard which defines these codes.

=item http://www.din.de/gremien/nas/nabd/iso3166ma/

Official home page for ISO 3166

=item http://www.egt.ie/standards/iso3166/iso3166-1-en.html

Another useful, but not official, home page.

=item http://www.cia.gov/cia/publications/factbook/docs/app-f.html

An appendix in the CIA world fact book which lists country codes
as defined by ISO 3166, FIPS 10-4, and internet domain names.

=back


=head1 AUTHOR

Neil Bowers E<lt>neil@bowers.comE<gt>

=head1 COPYRIGHT

Copyright (C) 2002, Neil Bowers.

Copyright (c) 1997-2001 Canon Research Centre Europe (CRE).

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

=cut