Format(3)

NAME
Number::Format - Perl extension for formatting numbers

SYNOPSIS
  use Number::Format;
  my $x = new Number::Format %args;
  $formatted = $x->round($number, $precision);
  $formatted = $x->format_number($number, $precision, $trailing_zeroes);
  $formatted = $x->format_negative($number, $picture);
  $formatted = $x->format_picture($number, $picture);
  $formatted = $x->format_price($number, $precision);
  $formatted = $x->format_bytes($number, $precision);
  $number    = $x->unformat_number($formatted);

  use Number::Format qw(:subs);
  $formatted = round($number, $precision);
  $formatted = format_number($number, $precision, $trailing_zeroes);
  $formatted = format_negative($number, $picture);
  $formatted = format_picture($number, $picture);
  $formatted = format_price($number, $precision);
  $formatted = format_bytes($number, $precision);
  $number    = unformat_number($formatted);

REQUIRES
Perl, version 5.003 or higher.

POSIX.pm will be used if present to determine locale settings.

Carp.pm is used for some error reporting.

DESCRIPTION
These functions provide an easy means of formatting numbers in a manner suitable for displaying to the user.

There are two ways to use this package. One is to declare an object of type Number::Format, which you can think of as a formatting engine. The various functions defined here are provided as object methods. The constructor "new()" can be used to set the parameters of the formatting engine. Valid parameters are:

  THOUSANDS_SEP     - character inserted between groups of 3 digits
  DECIMAL_POINT     - character separating integer and fractional parts
  MON_THOUSANDS_SEP - like THOUSANDS_SEP, but used for format_price
  MON_DECIMAL_POINT - like DECIMAL_POINT, but used for format_price
  INT_CURR_SYMBOL   - character(s) denoting currency (see format_price())
  DECIMAL_DIGITS    - number of digits to the right of dec point (def 2)
  DECIMAL_FILL      - boolean; whether to add zeroes to fill out decimal
  NEG_FORMAT        - format to display negative numbers (def ``-x'')
  KILO_SUFFIX       - suffix to add when format_bytes formats kilobytes
  MEGA_SUFFIX       -    "    "  "    "        "         "    megabytes
  GIGA_SUFFIX       -    "    "  "    "        "         "    gigabytes

They may be specified in upper or lower case, with or without a leading hyphen ( - ).

The defaults for "THOUSANDS_SEP", "DECIMAL_POINT", "MON_THOUSANDS_SEP", "MON_DECIMAL_POINT", and "INT_CURR_SYMBOL" come from the POSIX locale information (see perllocale), if available. If your POSIX locale does not provide "MON_THOUSANDS_SEP" and/or "MON_DECIMAL_POINT" fields, then the "THOUSANDS_SEP" and/or "DECIMAL_POINT" values are used for those parameters. Some systems (e.g. Win32 ports of Perl) do not include POSIX support. In those systems, the POSIX system is bypassed.

If any of the above parameters are not specified when you invoke "new()", then the values are taken from package global variables of the same name (e.g. $DECIMAL_POINT is the default for the "DECIMAL_POINT" parameter). If you use the ":vars" keyword on your "use Number::Format" line (see non-object-oriented example below) you will import those variables into your namesapce and can assign values as if they were your own local variables. The default values for all the parameters are:

  THOUSANDS_SEP     = ','
  DECIMAL_POINT     = '.'
  MON_THOUSANDS_SEP = ','
  MON_DECIMAL_POINT = '.'
  INT_CURR_SYMBOL   = 'USD'
  DECIMAL_DIGITS    = 2
  DECIMAL_FILL      = 0
  NEG_FORMAT        = '-x'
  KILO_SUFFIX       = 'K'
  MEGA_SUFFIX       = 'M'
  GIGA_SUFFIX       = 'G'

Note however that when you first call one of the functions in this module without using the object-oriented interface, further setting of those global variables will have no effect on non-OO calls. It is recommended that you use the object-oriented interface instead for fewer headaches and a cleaner design.

The "DECIMAL_FILL" and "DECIMAL_DIGITS" values are not set by the Locale system, but are definable by the user. They affect the output of "format_number()". Setting "DECIMAL_DIGITS" is like giving that value as the $precision argument to that function. Setting "DECIMAL_FILL" to a true value causes "format_number()" to append zeroes to the right of the decimal digits until the length is the specified number of digits.

"NEG_FORMAT" is only used by "format_negative()" and is a string containing the letter 'x', where that letter will be replaced by a positive representation of the number being passed to that function. "format_number()" and "format_price()" utilize this feature by calling "format_negative()" if the number was less than 0.

"KILO_SUFFIX", "MEGA_SUFFIX", and "GIGA_SUFFIX" are used by "format_bytes()" when the value is over 1024, 1024*1024, or 1024*1024*1024, respectively. The default values are "K", "M", and "G". Note: we can't do TERA because of integer overflows on 32-bit systems.

The only restrictions on "DECIMAL_POINT" and "THOUSANDS_SEP" are that they must not be digits, must not be identical, and must each be one character. There are no restrictions on "INT_CURR_SYMBOL".

For example, a German user might include this in their code:

  use Number::Format;
  my $de = new Number::Format(-thousands_sep   => '.',
                              -decimal_point   => ',',
                              -int_curr_symbol => 'DEM');
  my $formatted = $de->format_number($number);

Or, if you prefer not to use the object oriented interface, you can do this instead:

  use Number::Format qw(:subs :vars);
  $THOUSANDS_SEP   = '.';
  $DECIMAL_POINT   = ',';
  $INT_CURR_SYMBOL = 'DEM';
  my $formatted = format_number($number);

EXPORTS
Nothing is exported by default. To export the functions or the global variables defined herein, specify the function name(s) on the import list of the "use Number::Format" statement. To export all functions defined herein, use the special tag ":subs". To export the variables, use the special tag ":vars"; to export both subs and vars you can use the tag ":all".

METHODS

new( %args )
    Creates a new Number::Format object. Valid keys for %args are any of the parameters described above. Keys may be in all uppercase or all lowercase, and may optionally be preceded by a hyphen (-) character. Example:

      my $de = new Number::Format(-thousands_sep   => '.',
                                  -decimal_point   => ',',
                                  -int_curr_symbol => 'DEM');

round($number, $precision)
    Rounds the number to the specified precision. If $precision is omitted, the value of the "DECIMAL_DIGITS" parameter is used (default value 2). Both input and output are numeric (the function uses math operators rather than string manipulation to do its job), The value of $precision may be any integer, positive or negative. Examples:

      round(3.14159)       yields    3.14
      round(3.14159, 4)    yields    3.1416
      round(42.00, 4)      yields    42
      round(1234, -2)      yields    1200

    Since this is a mathematical rather than string oriented function, there will be no trailing zeroes to the right of the decimal point, and the "DECIMAL_POINT" and "THOUSANDS_SEP" variables are ignored. To format your number using the "DECIMAL_POINT" and "THOUSANDS_SEP" variables, use "format_number()" instead.

format_number($number, $precision, $trailing_zeroes)
    Formats a number by adding "THOUSANDS_SEP" between each set of 3 digits to the left of the decimal point, substituting "DECIMAL_POINT" for the decimal point, and rounding to the specified precision using "round()". Note that $precision is a maximum precision specifier; trailing zeroes will only appear in the output if $trailing_zeroes is provided, or the parameter "DECIMAL_FILL" is set, with a value that is true (not zero, undef, or the empty string). If $precision is omitted, the value of the "DECIMAL_DIGITS" parameter (default value of 2) is used. Examples:

      format_number(12345.6789)      yields   '12,345.68'
      format_number(123456.789, 2)   yields   '123,456.79'
      format_number(1234567.89, 2)   yields   '1,234,567.89'
      format_number(1234567.8, 2)    yields   '1,234,567.8'
      format_number(1234567.8, 2, 1) yields   '1,234,567.80'
      format_number(1.23456789, 6)   yields   '1.234568'

    Of course the output would have your values of "THOUSANDS_SEP" and "DECIMAL_POINT" instead of ',' and '.' respectively.

format_negative($number, $picture)
    Formats a negative number. Picture should be a string that contains the letter "x" where the number should be inserted. For example, for standard negative numbers you might use ``"-x"'', while for accounting purposes you might use ``"(x)"''. If the specified number begins with a ``-'' character, that will be removed before formatting, but formatting will occur whether or not the number is negative.

format_picture($number, $picture)
    Returns a string based on $picture with the "#" characters replaced by digits from $number. If the length of the integer part of $number is too large to fit, the "#" characters are replaced with asterisks ("*") instead. Examples:

      format_picture(100.023, 'USD ##,###.##')   yields   'USD    100.02'
      format_picture(1000.23, 'USD ##,###.##')   yields   'USD  1,000.23'
      format_picture(10002.3, 'USD ##,###.##')   yields   'USD 10,002.30'
      format_picture(100023,  'USD ##,###.##')   yields   'USD **,***.**'
      format_picture(1.00023, 'USD #.###,###')   yields   'USD 1.002,300'

    The comma (,) and period (.) you see in the picture examples should match the values of "THOUSANDS_SEP" and "DECIMAL_POINT", respectively, for proper operation. However, the "THOUSANDS_SEP" characters in $picture need not occur every three digits; the only use of that variable by this function is to remove leading commas (see the first example above). There may not be more than one instance of "DECIMAL_POINT" in $picture.

    The value of "NEG_FORMAT" is used to determine how negative numbers are displayed. The result of this is that the output of this function my have unexpected spaces before and/or after the number. This is necessary so that positive and negative numbers are formatted into a space the same size. If you are only using positive numbers and want to avoid this problem, set NEG_FORMAT to "x".

format_price($number, $precision)
    Returns a string containing $number formatted similarly to "format_number()", except that the decimal portion may have trailing zeroes added to make it be exactly $precision characters long, and the currency string will be prefixed.

    If the "INT_CURR_SYMBOL" attribute of the object is the empty string, no currency will be added.

    If $precision is not provided, the default of 2 will be used. Examples:

      format_price(12.95)   yields   'USD 12.95'
      format_price(12)      yields   'USD 12.00'
      format_price(12, 3)   yields   '12.000'

    The third example assumes that "INT_CURR_SYMBOL" is the empty string.

format_bytes($number, $precision)
    Returns a string containing $number formatted similarly to "format_number()", except that if the number is over 1024, it will be divided by 1024 and "K" appended to the end; or if it is over 1048576 (1024*1024), it will be divided by 1048576 and "M" appended to the end. Negative values will result in an error.

    If $precision is not provided, the default of 2 will be used. Examples:

      format_bytes(12.95)   yields   '12.95'
      format_bytes(2048)    yields   '2K'
      format_bytes(1048576) yields   '1M'

unformat_number($formatted)
    Converts a string as returned by "format_number()", "format_price()", or "format_picture()", and returns the corresponding value as a numeric scalar. Returns "undef" if the number does not contain any digits. Examples:

      unformat_number('USD 12.95')   yields   12.95
      unformat_number('USD 12.00')   yields   12
      unformat_number('foobar')      yields   undef
      unformat_number('1234-567@.8') yields   1234567.8

    The value of "DECIMAL_POINT" is used to determine where to separate the integer and decimal portions of the input. All other non-digit characters, including but not limited to "INT_CURR_SYMBOL" and "THOUSANDS_SEP", are removed.

    If the number matches the pattern of "NEG_FORMAT" or there is a ``-'' character before any of the digits, then a negative number is returned.

    If the number ends with the "KILO_SUFFIX" or "MEGA_SUFFIX" characters, then the number returned will be multiplied by 1024 or 1024*1024 as appropriate.

BUGS
No known bugs at this time. Please report any problems to the author.

AUTHOR
William R. Ward, wrw@bayview.com

SEE ALSO
perl(1).