Forcing four-digit years on IntlDateFormatter::SHORT

formattingtest.php

<?php

$d = new DateTime("2012-10-11");

function unalteredFormat($date, $locale) {
    $fmt = new IntlDateFormatter(
        $locale,
        IntlDateFormatter::SHORT,
        IntlDateFormatter::NONE);
    $fmtted = $fmt->format($date);
    echo "$locale: $fmtted\n";
}

function modifiedFormat($date, $locale) {
    $fmt = new IntlDateFormatter(
        $locale,
        IntlDateFormatter::SHORT,
        IntlDateFormatter::NONE);
    $pattern = $fmt->getPattern();
    $pattern = preg_replace(
        '/(?<!y)yy(?!y)/',
        'yyyy',
        $pattern);
    $fmt->setPattern($pattern);

    $fmtted = $fmt->format($date);
    echo "$locale: $fmtted\n";
}

$locales = array(
    'en_US',
    'en_GB',
    'de_DE',
    'fr_FR',
    'ru_RU',
    'en_ZW',
    'ps_AF',
);

echo "-- Unaltered format --\n";
foreach ($locales as $locale) {
    unalteredFormat($d, $locale);
}

echo "\n";

echo "-- Modified format --\n";
foreach ($locales as $locale) {
    modifiedFormat($d, $locale);
}

output.txt

-- Unaltered format --
en_US: 10/11/12
en_GB: 11/10/2012
de_DE: 11.10.12
fr_FR: 11/10/2012
ru_RU: 11.10.12
en_ZW: 11/10/2012
ps_AF: م. ۲۰۱۲/۱۰/۱۱

-- Modified format --
en_US: 10/11/2012
en_GB: 11/10/2012
de_DE: 11.10.2012
fr_FR: 11/10/2012
ru_RU: 11.10.2012
en_ZW: 11/10/2012
ps_AF: م. ۲۰۱۲/۱۰/۱۱