It is important to know that floats are actually locale aware in PHP. I’m not sure if that have always been the case. The below code will actually output 10,5 as Swedish use “,” as decimal point.

setlocale(LC_ALL, 'sv_SE.UTF-8');
echo 10.5;

The test in Zend_Validate_Float looked like

$locale = localeconv();

$valueFiltered = str_replace($locale['thousands_sep'], '', $valueString);
$valueFiltered = str_replace($locale['decimal_point'], '.', $valueFiltered);

if (strval(floatval($valueFiltered)) != $valueFiltered) {
  $this->_error();
  return false;
}

Under the Swedish locale mentioned above this will result in a comparison between two strings; “10,5″ and “10.5″.

I have proposed the following solution.

$locale = localeconv();

$valueFiltered = str_replace($locale['thousands_sep'], '', $valueString);
$valueFiltered = str_replace($locale['decimal_point'], '.', $valueFiltered);

list($num, $dec) = explode('.', $valueFiltered);
if (strval(intval($num)) != $num || strval(intval($dec)) != $dec) {
  $this->_error();
  return false;
}

But I just realized that it can be further simplified.

$locale = localeconv();

$valueFiltered = str_replace($locale['thousands_sep'], '', $valueString);

list($num, $dec) = explode($locale['decimal_point'], $valueFiltered);
if (strval(intval($num)) != $num || strval(intval($dec)) != $dec) {
  $this->_error();
  return false;
}