Locale-Aware Formatting

Also Known As

TL;DR

Explanation

PHP's Intl extension (ICU-based) provides locale-aware formatting: NumberFormatter (numbers, currencies, percentages), DateFormatter (dates, times with locale-specific patterns), and MessageFormatter (pluralisation rules, placeholders). Locale identifiers use BCP 47 format (en-US, de-DE, zh-Hans-CN). Formatting must happen at the presentation layer — store raw values (1234.56, timestamps in UTC) and format for display.

Common Misconception

Why It Matters

Common Mistakes

• Hardcoding currency symbols — $ means dollars only in en-US context; use NumberFormatter with the currency code.
• Manual date string replacement for localisation — different locales have completely different date structures.
• Not handling pluralisation with MessageFormatter — '1 item' vs '2 items' varies by language in non-obvious ways.
• Assuming number formatting is sufficient — order of day/month/year varies by locale and cannot be fixed by number formatting alone.

Code Examples

// Manual locale formatting — fragile:
$price = 1234.56;
echo '€' . number_format($price, 2, ',', '.'); // '€1.234,56'
// Hardcoded to German format — wrong for French (1 234,56 €)

// Intl NumberFormatter — correct for any locale:
$formatter = new NumberFormatter('de-DE', NumberFormatter::CURRENCY);
echo $formatter->formatCurrency(1234.56, 'EUR'); // '1.234,56 €'

$formatter = new NumberFormatter('fr-FR', NumberFormatter::CURRENCY);
echo $formatter->formatCurrency(1234.56, 'EUR'); // '1 234,56 €'

// Date formatting:
$fmt = new IntlDateFormatter('de-DE', IntlDateFormatter::LONG, IntlDateFormatter::NONE);
echo $fmt->format(new DateTime('2026-03-15')); // '15. März 2026'

References

• ↗ https://www.php.net/manual/en/class.numberformatter.php

Tags

Related Terms