In reply to daniel at danielphenry dot com example note beneath. The given example by Daniel returns false under PHP7.x, which is a normal behavior since NumberFormatter::parseCurrency() is a method for parsing currency strings. It is trying to split up the given string in a float and a currency. 

While using strict types under PHP7 the following example makes it more clearer.

<?php
declare(strict_types=1);
namespace MMNewmedia;

$oParser = new \NumberFormatter('de_DE', \NumberFormatter::CURRENCY);
var_dump($oParser->parseCurrency("1.234.567,89\xc2\xa0€", $currency), $currency));
?>

This example returns: "float(1234567.89) string(3) "EUR"

This is the expected behavior.

The following example runs into a type error, which is absolutely right, since this method is vor parsing strings and not vor formatting floats into currency strings.

<?php
declare(strict_types=1);
namespace MMNewmedia;

try {
    $oCurrencyParser = new \NumberFormatter('de_DE', \NumberFormatter::CURRENCY);
    $currency = 'EUR';
    var_dump($oCurrencyParser->parseCurrency(1.234, $currency), $currency);
} catch (\TypeError $oTypeError) {
    var_dump($oTypeError->getMessage());
}
?>

This example returns "NumberFormatter::parseCurrency() expects parameter 1 to be string, float given".

If you want to parse floats into a currency string use the http://php.net/manual/en/numberformatter.formatcurrency.php method as shown in the next example.

<?php
declare(strict_types=1);
namespace MMNewmedia;

$oFormatter = new \NumberFormatter('de_DE', \NumberFormatter::CURRENCY);
var_dump($oFormatter->formatCurrency(1234567.89, 'EUR'));
?>

This returns string(17) "1.234.567,89 €" as expected.