The NumberFormatter class
Введение
Programs store and operate on numbers using a locale-independent binary representation. When displaying or printing a number it is converted to a locale-specific string. For example, the number 12345.67 is "12,345.67" in the US, "12 345,67" in France and "12.345,67" in Germany.
By invoking the methods provided by the NumberFormatter class, you can format numbers, currencies, and percentages according to the specified or default locale. NumberFormatter is locale-sensitive so you need to create a new NumberFormatter for each locale. NumberFormatter methods format primitive-type numbers, such as double and output the number as a locale-specific string.
For currencies you can use currency format type to create a formatter that returns a string with the formatted number and the appropriate currency sign. Of course, the NumberFormatter class is unaware of exchange rates so, the number output is the same regardless of the specified currency. This means that the same number has different monetary values depending on the currency locale. If the number is 9988776.65 the results will be:
- 9 988 776,65 € in France
- 9.988.776,65 € in Germany
- $9,988,776.65 in the United States
In order to format percentages, create a locale-specific formatter with percentage format type. With this formatter, a decimal fraction such as 0.75 is displayed as 75%.
For more complex formatting, like spelled-out numbers, the rule-based number formatters are used.
Class synopsis
Предопределенные константы
These styles are used by the numfmt_create() to define the type of the formatter.
- NumberFormatter::PATTERN_DECIMAL (integer)
- Decimal format defined by pattern
- NumberFormatter::DECIMAL (integer)
- Decimal format
- NumberFormatter::CURRENCY (integer)
- Currency format
- NumberFormatter::PERCENT (integer)
- Percent format
- NumberFormatter::SCIENTIFIC (integer)
- Scientific format
- NumberFormatter::SPELLOUT (integer)
- Spellout rule-based format
- NumberFormatter::ORDINAL (integer)
- Ordinal rule-based format
- NumberFormatter::DURATION (integer)
- Duration rule-based format
- NumberFormatter::PATTERN_RULEBASED (integer)
- Rule-based format defined by pattern
- NumberFormatter::DEFAULT_STYLE (integer)
- Default format for the locale
- NumberFormatter::IGNORE (integer)
- Alias for PATTERN_DECIMAL
These constants define how the numbers are parsed or formatted. They should be used as arguments to numfmt_format() and numfmt_parse().
- NumberFormatter::TYPE_DEFAULT (integer)
- Derive the type from variable type
- NumberFormatter::TYPE_INT32 (integer)
- Format/parse as 32-bit integer
- NumberFormatter::TYPE_INT64 (integer)
- Format/parse as 64-bit integer
- NumberFormatter::TYPE_DOUBLE (integer)
- Format/parse as floating point value
- NumberFormatter::TYPE_CURRENCY (integer)
- Format/parse as currency value
Number format attribute used by numfmt_get_attribute() and numfmt_set_attribute() .
- NumberFormatter::PARSE_INT_ONLY (integer)
- Parse integers only.
- NumberFormatter::GROUPING_USED (integer)
- Use grouping separator.
- NumberFormatter::DECIMAL_ALWAYS_SHOWN (integer)
- Always show decimal point.
- NumberFormatter::MAX_INTEGER_DIGITS (integer)
- Maximum integer digits.
- NumberFormatter::MIN_INTEGER_DIGITS (integer)
- Minimum integer digits.
- NumberFormatter::INTEGER_DIGITS (integer)
- Integer digits.
- NumberFormatter::MAX_FRACTION_DIGITS (integer)
- Maximum fraction digits.
- NumberFormatter::MIN_FRACTION_DIGITS (integer)
- Minimum fraction digits.
- NumberFormatter::FRACTION_DIGITS (integer)
- Fraction digits.
- NumberFormatter::MULTIPLIER (integer)
- Multiplier.
- NumberFormatter::GROUPING_SIZE (integer)
- Grouping size.
- NumberFormatter::ROUNDING_MODE (integer)
- Rounding Mode.
- NumberFormatter::ROUNDING_INCREMENT (integer)
- Rounding increment.
- NumberFormatter::FORMAT_WIDTH (integer)
- The width to which the output of format() is padded.
- NumberFormatter::PADDING_POSITION (integer)
- The position at which padding will take place. See pad position constants for possible argument values.
- NumberFormatter::SECONDARY_GROUPING_SIZE (integer)
- Secondary grouping size.
- NumberFormatter::SIGNIFICANT_DIGITS_USED (integer)
- Use significant digits.
- NumberFormatter::MIN_SIGNIFICANT_DIGITS (integer)
- Minimum significant digits.
- NumberFormatter::MAX_SIGNIFICANT_DIGITS (integer)
- Maximum significant digits.
- NumberFormatter::LENIENT_PARSE (integer)
- Lenient parse mode used by rule-based formats.
Number format text attribute used by numfmt_get_text_attribute() and numfmt_set_text_attribute().
- NumberFormatter::POSITIVE_PREFIX (integer)
- Positive prefix.
- NumberFormatter::POSITIVE_SUFFIX (integer)
- Positive suffix.
- NumberFormatter::NEGATIVE_PREFIX (integer)
- Negative prefix.
- NumberFormatter::NEGATIVE_SUFFIX (integer)
- Negative suffix.
- NumberFormatter::PADDING_CHARACTER (integer)
- The character used to pad to the format width.
- NumberFormatter::CURRENCY_CODE (integer)
- The ISO currency code.
- NumberFormatter::DEFAULT_RULESET (integer)
- The default rule set. This is only available with rule-based formatters.
- NumberFormatter::PUBLIC_RULESETS (integer)
- The public rule sets. This is only available with rule-based formatters. This is a read-only attribute. The public rulesets are returned as a single string, with each ruleset name delimited by ';' (semicolon).
Number format symbols used by numfmt_get_symbol() and numfmt_set_symbol().
- NumberFormatter::DECIMAL_SEPARATOR_SYMBOL (integer)
- The decimal separator.
- NumberFormatter::GROUPING_SEPARATOR_SYMBOL (integer)
- The grouping separator.
- NumberFormatter::PATTERN_SEPARATOR_SYMBOL (integer)
- The pattern separator.
- NumberFormatter::PERCENT_SYMBOL (integer)
- The percent sign.
- NumberFormatter::ZERO_DIGIT_SYMBOL (integer)
- Zero.
- NumberFormatter::DIGIT_SYMBOL (integer)
- Character representing a digit in the pattern.
- NumberFormatter::MINUS_SIGN_SYMBOL (integer)
- The minus sign.
- NumberFormatter::PLUS_SIGN_SYMBOL (integer)
- The plus sign.
- NumberFormatter::CURRENCY_SYMBOL (integer)
- The currency symbol.
- NumberFormatter::INTL_CURRENCY_SYMBOL (integer)
- The international currency symbol.
- NumberFormatter::MONETARY_SEPARATOR_SYMBOL (integer)
- The monetary separator.
- NumberFormatter::EXPONENTIAL_SYMBOL (integer)
- The exponential symbol.
- NumberFormatter::PERMILL_SYMBOL (integer)
- Per mill symbol.
- NumberFormatter::PAD_ESCAPE_SYMBOL (integer)
- Escape padding character.
- NumberFormatter::INFINITY_SYMBOL (integer)
- Infinity symbol.
- NumberFormatter::NAN_SYMBOL (integer)
- Not-a-number symbol.
- NumberFormatter::SIGNIFICANT_DIGIT_SYMBOL (integer)
- Significant digit symbol.
- NumberFormatter::MONETARY_GROUPING_SEPARATOR_SYMBOL (integer)
- The monetary grouping separator.
Rounding mode values used by numfmt_get_attribute() and numfmt_set_attribute() with NumberFormatter::ROUNDING_MODE attribute.
- NumberFormatter::ROUND_CEILING (integer)
- Rounding mode to round towards positive infinity.
- NumberFormatter::ROUND_DOWN (integer)
- Rounding mode to round towards zero.
- NumberFormatter::ROUND_FLOOR (integer)
- Rounding mode to round towards negative infinity.
- NumberFormatter::ROUND_HALFDOWN (integer)
- Rounding mode to round towards "nearest neighbor" unless both neighbors are equidistant, in which case round down.
- NumberFormatter::ROUND_HALFEVEN (integer)
- Rounding mode to round towards the "nearest neighbor" unless both neighbors are equidistant, in which case, round towards the even neighbor.
- NumberFormatter::ROUND_HALFUP (integer)
- Rounding mode to round towards "nearest neighbor" unless both neighbors are equidistant, in which case round up.
- NumberFormatter::ROUND_UP (integer)
- Rounding mode to round away from zero.
Pad position values used by numfmt_get_attribute() and numfmt_set_attribute() with NumberFormatter::PADDING_POSITION attribute.
- NumberFormatter::PAD_AFTER_PREFIX (integer)
- Pad characters inserted after the prefix.
- NumberFormatter::PAD_AFTER_SUFFIX (integer)
- Pad characters inserted after the suffix.
- NumberFormatter::PAD_BEFORE_PREFIX (integer)
- Pad characters inserted before the prefix.
- NumberFormatter::PAD_BEFORE_SUFFIX (integer)
- Pad characters inserted before the suffix.
Содержание
- NumberFormatter::create — Create a number formatter
- NumberFormatter::formatCurrency — Format a currency value
- NumberFormatter::format — Format a number
- NumberFormatter::getAttribute — Get an attribute
- NumberFormatter::getErrorCode — Get formatter's last error code.
- NumberFormatter::getErrorMessage — Get formatter's last error message.
- NumberFormatter::getLocale — Get formatter locale
- NumberFormatter::getPattern — Get formatter pattern
- NumberFormatter::getSymbol — Get a symbol value
- NumberFormatter::getTextAttribute — Get a text attribute
- NumberFormatter::parseCurrency — Parse a currency number
- NumberFormatter::parse — Parse a number
- NumberFormatter::setAttribute — Set an attribute
- NumberFormatter::setPattern — Set formatter pattern
- NumberFormatter::setSymbol — Set a symbol value
- NumberFormatter::setTextAttribute — Set a text attribute
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Коментарии
Sample script to print number in English.
<?php
$f = new NumberFormatter("en", NumberFormatter::SPELLOUT);
echo $f->format(123456);
?>
Produces the result:
one hundred twenty-three thousand four hundred fifty-six
this class seems to be painful: it is not, formatting and parsing are highly customizable, but what you probably need is really simple:
if you want to localize a number use:
<?php
$a = new \NumberFormatter("it-IT", \NumberFormatter::DECIMAL);
echo $a->format(12345.12345) . "<br>"; // outputs 12.345,12
$a->setAttribute(\NumberFormatter::MIN_FRACTION_DIGITS, 0);
$a->setAttribute(\NumberFormatter::MAX_FRACTION_DIGITS, 100); // by default some locales got max 2 fraction digits, that is probably not what you want
echo $a->format(12345.12345) . "<br>"; // outputs 12.345,12345
?>
if you want to print money use:
<?php
$a = new \NumberFormatter("it-IT", \NumberFormatter::CURRENCY);
echo $a->format(12345.12345) . "<br>"; // outputs €12.345,12
?>
if you have money data stored as (for example) US dollars and you want to print them using the it-IT notation, you need to use
<?php
$a = new \NumberFormatter("it-IT", \NumberFormatter::CURRENCY);
echo $a->formatCurrency(12345, "USD") . "<br>"; // outputs $ 12.345,00 and it is formatted using the italian notation (comma as decimal separator)
?>
another useful example about currency (how to obtain the currency name by a locale string):
<?php
$frontEndFormatter = new \NumberFormatter("it-IT", \NumberFormatter::CURRENCY);
$adminFormatter = new \NumberFormatter("en-US", \NumberFormatter::CURRENCY);
$symbol = $adminFormatter->getSymbol(\NumberFormatter::INTL_CURRENCY_SYMBOL); // got USD
echo $frontEndFormatter->formatCurrency(12345.12345, $symbol) . "<br>";
?>
Be warned that this class sometimes lacks sufficient error output. I recently instantiated it while invalid pattern to the constructor.
php -r '$nf = new \NumberFormatter("tlh-KX.UTF8", \NumberFormatter::IGNORE, "{,,#;#}");var_dump($nf->format(5));'
Fatal error: Call to a member function format() on null in Command line code on line 1
Rather than emitting an error message or throwing an exception null is returned after calling new.
I'm not sure if it's fixed in PHP 7 but it's something to watch out for. Make sure you check your parameters very closely.
Here's an example of how to use PATTERN_DECIMAL to print a number with two fraction digits, use () for negative numbers and pad to five characters to the left of the decimal point, using spaces as the padding character:
<?php
$fmt = new NumberFormatter("en-CA", NumberFormatter::PATTERN_DECIMAL, "* #####.00 ;(* #####.00)");
echo $fmt->format(-45.1);
// Outputs: " (45.10)"
?>
Note that the ; in the pattern denotes the beginning of a subpattern, which is used for negative numbers. Hence the brackets around the pattern after the semicolon.
Please pay attention to the Arabic decimal separator (https://en.wikipedia.org/wiki/Decimal_separator#Other_numeral_systems).
All the following conditions are true:
<?php
(new \NumberFormatter("ar_AE", \NumberFormatter::DEFAULT_STYLE))->getSymbol(\NumberFormatter::DECIMAL_SEPARATOR_SYMBOL) === '٫';
(new \NumberFormatter("ar_AE", \NumberFormatter::DEFAULT_STYLE))->getSymbol(\NumberFormatter::DECIMAL_SEPARATOR_SYMBOL) == '٫';
(new \NumberFormatter("ar_AE", \NumberFormatter::DEFAULT_STYLE))->getSymbol(\NumberFormatter::DECIMAL_SEPARATOR_SYMBOL) !== ',';
(new \NumberFormatter("ar_AE", \NumberFormatter::DEFAULT_STYLE))->getSymbol(\NumberFormatter::DECIMAL_SEPARATOR_SYMBOL) != ',';
?>
When using the `NumberFormatter` class for pretty-printing currency in PHP 7.3 and 8+, it's not clear from the documentation that you can use the empty string "" as the locale for the constructor, and that will retrieve the default locale (whatever it has been set to in your environment).
`formatCurrency()`, by contrast, does not accept the empty string for the default currency symbol; it will display a 'generic' currency symbol instead (¤).
Tested with PHP 7.4.30, 8.0.21, 8.1.8 under Ubuntu Linux and 8.1.8 under macOS Big Sur (11.6.8). I tried under other alternatives (e.g. Linux running on ARM chips, PHP 7.3.3) but sadly the `NumberFormatter` library does not seem to be present (or could not be found) on those systems...
The NumberFormatter class can be used to convert integer numbers to Roman numerals without a custom function using an array of symbols and associated values:
<?php
function intToRomanNumeral(int $num) {
static $nf = new NumberFormatter('@numbers=roman', NumberFormatter::DECIMAL);
return $nf->format($num);
}
echo intToRomanNumeral(2); // II
echo intToRomanNumeral(5); // V
echo intToRomanNumeral(10); // X
echo intToRomanNumeral(50); // L
echo intToRomanNumeral(57); // LVII
echo intToRomanNumeral(58); // LVIII
echo intToRomanNumeral(100); // C
echo intToRomanNumeral(150); // CL
echo intToRomanNumeral(1000); // M
echo intToRomanNumeral(10000); // ↂ
?>
Be aware that (at least with the locale 'fr-FR') NumberFormatter doesn't use spaces. It doesn't even use non breakable spaces (NBSP). It uses narrow non breakable spaces (NNBSP). This broke my tests.
<?php
$formatter = new NumberFormatter(
'fr-FR',
NumberFormatter::DEFAULT_STYLE
);
$value = $formatter->format(100_000); // '100 000'
// If you want to replace narrow non breakable spaces with non breakable spaces:
str_replace("\u{202F}", "\u{00A0}", $value);
// If you want to replace it with a normal space
str_replace("\u{202F}", " ", $value);