Localized (short) month names using IntlDateFormatter in PHP?

On my Windows development machine, I have set the locale to ita:

setlocale(LC_TIME, 'ita');
echo strftime('%b'); // dic

While (I suppose, can't test right now) on a *nix system, I should use it:

setlocale(LC_TIME, 'it');

If I try to set it on my Windows it doesn't work, printing Dec.

It seems I can't rely on setlocale(), so I should use IntlDateFormatter as suggested by @hakre. However, I can find the constant that gives me the month name and the short one:

IntlDateFormatter::NONE (integer)
Do not include this element

IntlDateFormatter::FULL (integer)
Completely specified style (Tuesday, April 12, 1952 AD or 3:30:42pm PST)

IntlDateFormatter::LONG (integer)
Long style (January 12, 1952 or 3:30:32pm)

IntlDateFormatter::MEDIUM (integer)
Medium style (Jan 12, 1952)

IntlDateFormatter::SHORT (integer)
Most abbreviated style, only essential data (12/13/52 or 3:30pm)

Solution

From the reference, some month formatting codes:

Symbol     Meaning             Example:            

M          month in year       M or MM    09       
                               MMM        Sept     
                               MMMM       September
                               MMMMM      S

The PHP function to set the format is: IntlDateFormatter::setPattern, some examples:

class LocaleDateFormat
{
    private $locale;
    private $pattern;

    public function __construct($pattern, $locale = 'en_US') {
        $this->setLocale($locale);
        $this->setPattern($pattern);
    }

    public function setLocale($locale) {
        $this->locale = $locale;
    }

    public function setPattern($pattern) {
        $this->pattern = $pattern;
    }

    public function localeFormat($locale, $date) {
        $this->setLocale($locale);
        return $this->format($date);
    }

    public function format($date) {
        $formatter = new IntlDateFormatter($this->locale, IntlDateFormatter::FULL, IntlDateFormatter::FULL);
        $formatter->setPattern($this->pattern);
        return $formatter->format($date);
    }
}

$dateFormat = new LocaleDateFormat('MMMM'); # Long Month Names

$date = new DateTime(); # Now

$locales = ["en_US", "de_DE", "sv_SE", "ru_RU"];
foreach ($locales as $i => $locale) {
    $month = $dateFormat->localeFormat($locale, $date);
    printf("%d. %s - %s\n", $i+1, $locale, $month);
}

Output:

1. en_US - December
2. de_DE - Dezember
3. sv_SE - december
4. ru_RU - декабря

For a list of locales see here:

List of available collators in PHP?

The actual example for the short monthnames across different locales:

$locales    = ["en_US", "de_DE", "sv_SE", "ru_RU", 'it', 'it_IT', 'it_CH'];
$dateFormat = new LocaleDateFormat('MMM'); # Short Month Names

$date = new DateTime(); # Now

foreach (range(1, 12) as $monthNumber)
{
    $date->setDate(2012, $monthNumber, 1);

    printf("%02d:    ", $monthNumber);

    foreach ($locales as $locale)
    {
        $monthLabel = $dateFormat->localeFormat($locale, $date);
        $pad = str_repeat(' ', max(0, 8 - mb_strlen($monthLabel, 'UTF-8')));
        printf("%s: %s%s  ", $locale, $monthLabel, $pad);
    }

    echo "\n";
}

Exemplary output:

01:    en_US: Jan       de_DE: Jan       sv_SE: jan       ru_RU: янв.      it: gen       it_IT: gen       it_CH: gen       
02:    en_US: Feb       de_DE: Feb       sv_SE: feb       ru_RU: февр.     it: feb       it_IT: feb       it_CH: feb       
03:    en_US: Mar       de_DE: Mär       sv_SE: mar       ru_RU: марта     it: mar       it_IT: mar       it_CH: mar       
04:    en_US: Apr       de_DE: Apr       sv_SE: apr       ru_RU: апр.      it: apr       it_IT: apr       it_CH: apr       
05:    en_US: May       de_DE: Mai       sv_SE: maj       ru_RU: мая       it: mag       it_IT: mag       it_CH: mag       
06:    en_US: Jun       de_DE: Jun       sv_SE: jun       ru_RU: июня      it: giu       it_IT: giu       it_CH: giu       
07:    en_US: Jul       de_DE: Jul       sv_SE: jul       ru_RU: июля      it: lug       it_IT: lug       it_CH: lug       
08:    en_US: Aug       de_DE: Aug       sv_SE: aug       ru_RU: авг.      it: ago       it_IT: ago       it_CH: ago       
09:    en_US: Sep       de_DE: Sep       sv_SE: sep       ru_RU: сент.     it: set       it_IT: set       it_CH: set       
10:    en_US: Oct       de_DE: Okt       sv_SE: okt       ru_RU: окт.      it: ott       it_IT: ott       it_CH: ott       
11:    en_US: Nov       de_DE: Nov       sv_SE: nov       ru_RU: нояб.     it: nov       it_IT: nov       it_CH: nov       
12:    en_US: Dec       de_DE: Dez       sv_SE: dec       ru_RU: дек.      it: dic       it_IT: dic       it_CH: dic