locale(3p)

NAME
locale - Perl pragma to use or avoid POSIX locales for built-in operations

SYNOPSIS
    @x = sort @y;       # Unicode sorting order
    {
        use locale;
        @x = sort @y;   # Locale-defined sorting order
    }
    @x = sort @y;       # Unicode sorting order again

DESCRIPTION
This pragma tells the compiler to enable (or disable) the use of POSIX locales for built-in operations (for example, LC_CTYPE for regular expressions, LC_COLLATE for string comparison, and LC_NUMERIC for number formatting). Each "use locale" or "no locale" affects statements to the end of the enclosing BLOCK.

Starting in Perl 5.16, a hybrid mode for this pragma is available,

    use locale ':not_characters';

which enables only the portions of locales that don't affect the character set (that is, all except LC_COLLATE and LC_CTYPE). This is useful when mixing Unicode and locales, including UTF-8 locales.

    use locale ':not_characters';
    use open ":locale";           # Convert I/O to/from Unicode
    use POSIX qw(locale_h);       # Import the LC_ALL constant
    setlocale(LC_ALL, "");        # Required for the next statement
                                  # to take effect
    printf "%.2f\n", 12345.67'    # Locale-defined formatting
    @x = sort @y;                 # Unicode-defined sorting order.
                                  # (Note that you will get better
                                  # results using Unicode::Collate.)

See perllocale for more detailed information on how Perl supports locales.