PHP - Format currency

gistfile1.php

function formatCurrencySign($price, $currency, $separator = "")
    {
        if (!in_array($currency, array('USD', 'GBP', 'EUR')))
        {
            return $price . $separator . $currency;
        }
        switch ($currency)
        {
            case 'USD':
                $format = "$" . $separator . $price;
                break;
            case 'GBP':
                $format = "£" . $separator . $price;
                break;
            case 'EUR':
                $format = "€" . $separator . $price;
                break;
        }
        return $format;
}