Localize currency using encapsulated NumberFormatter functions

format_currency.php

<?php
/**
 * Localize currency using encapsulated NumberFormatter functions
 *
 * @param float $amount
 * @param array $args
 * @link https://www.php.net/manual/en/numberformatter.formatcurrency.php
 * @link https://www.php.net/manual/en/numberformatter.create.php
 * @link https://www.php.net/manual/en/class.locale.php
 * @link https://unicode.org/reports/tr35/tr35-numbers.html#table-number-pattern-character-definitions
 * @return string|false
 */
function format_currency($amount, array $args = []) {
    $args += [
        'locale'  => substr(Locale::getDefault(), 0, 5) ?: NULL,
        'pattern' => NULL,
        'style'   => NumberFormatter::CURRENCY,
    ];
    extract($args);
    $formatter = numfmt_create($locale, $style, $pattern);
    $symbol = numfmt_get_symbol($formatter, NumberFormatter::INTL_CURRENCY_SYMBOL);
    return numfmt_format_currency($formatter, $amount, $symbol);
}

function format_currency_accounting($amount, $space = FALSE, array $args = []) {
    $args += [
        'pattern' => $space ? '¤ #,##0.00;(¤ #,##0.00)' : '¤#,##0.00;(¤#,##0.00)',
        'style'   => NumberFormatter::PATTERN_DECIMAL,
    ];
    return format_currency($amount, $args);
}

numfmt_create() arguments

• https://www.php.net/manual/en/numberformatter.create.php

numfmt_create(string $locale, int $style, ?string $pattern = null): ?NumberFormatter

$locale

• https://www.php.net/manual/en/function.setlocale

If NULL, it will lookup its default value in this order:

1. ini_get('intl.default_locale')
2. setlocale(LC_ALL, '0');
3. $LANG value from the set locale of the operating system.

$style

• https://www.php.net/manual/en/class.numberformatter.php#intl.numberformatter-constants.unumberformatstyle

• For currency, it's NumberFormatter::CURRENCY.

• Starting at PHP version 7.4.1, there is NumberFormatter::CURRENCY_ACCOUNTING to format amounts with parentheses.

$pattern

• https://unicode.org/reports/tr35/tr35-numbers.html#table-number-pattern-character-definitions

• If not NULL, it will override the style argument.

• If NULL, it will defer to the style argument.