PHP formating numbers to locale and back - php

Question

After a lot of research I am actually using the following function to format numbers to the locale setted by the user:
function number_format_i18n($number, $decimals=0) {
$locale = localeconv();
return number_format($number,$decimals, $locale['decimal_point'], $locale['thousands_sep']);
}
I'll use this to format numbers from DB.
But if I have a form where a user can enter a number, I need a function to format it back so I can save into the DB. Here I found this solution:
function number_format_en($number) {
// $_SESSION['lang']['locale'] has the locale like de_DE, ar_AE, tr_TR, ...
$fmt = numfmt_create($_SESSION['lang']['locale'], NumberFormatter::DECIMAL);
return numfmt_parse($fmt, $number);
}
This works with the most locales I tested but not with everyone! As an example: if I use arabic (ar_AE):
$randomNumber = 3171003633.95;
$number2locale = number_format_i18n($randomNumber, 2);
// works as expected: 3,171,003,633.95
// now format it back:
$locale2number = number_format_en($number2locale);
// here I get this: 3.171
How can I format a locale entered number in a secure way "back" to en-format? Or is there a way to detect any kind of numberformat and format it to en-format so I can save it in the DB?

Answer 1

So, don't know really if this is a good solution or not - but it seems to be working fine:
function number_format_en($number) {
// first remove everything execpt -,.
$cleanNumber = preg_replace('/[^\\d-,.]+/', '', $number);
$last_dot = strrpos($cleanNumber, '.');
$last_comma = strrpos($cleanNumber, ',');
if($last_dot !== false || $last_comma !== false) {
if($last_dot > $last_comma) { // decimal seperator = dot
$decimal_point = '.';
if(substr_count($cleanNumber, '.') > 1) {
// could be totaly wrong 1,234.567.890
// or there are no decimals 1.234.567.890
// removing all dots and commas and returning the value
return preg_replace('/[^\\d-]+/', '', $cleanNumber);
}
} else { // decimal seperator = comma
$decimal_point = ',';
if(substr_count($cleanNumber, ',') > 1) {
// could be totaly wrong 1.234,567,890
// or there are no decimals 1,234,567,890
// removing all dots and commas and returning the value
return preg_replace('/[^\\d-]+/', '', $cleanNumber);
}
}
} else { // no decimals
$decimal_point = false;
$decimals = 0;
}
if($decimal_point !== false) {
// if decimals are delivered, get the count of them
$length = strlen($cleanNumber);
$position = strpos($cleanNumber, $decimal_point);
$decimals = $length - $position - 1;
if($decimal_point == '.') {
// remove all commas if seperator = .
$cleanNumber = str_replace(',', '', $cleanNumber);
} elseif($decimal_point == ',') {
// remove all dots if seperator = ,
$cleanNumber = str_replace('.', '', $cleanNumber);
// now switch comma with dot
$cleanNumber = str_replace(',', '.', $cleanNumber);
}
}
return $cleanNumber;
}
I'll check the last dot or comma and depending on that I format the number, function returns the same count of decimals as the original number. there is a "known" bug: if someone enters a full number like 1.000.000 or 1,000,000 it returns 1000000.
As an example:
number_format_en('1.234.567,89') // 1234567.89
number_format_en('-1,234,567.89') // -1234567.89
number_format_en('1.234.567.89') // 123456789 (only dots)
number_format_en('1,234,567,89') // 123456789 (only commas)
Would be nice if someone can post a comment if this is a good way or not or an answer with a better solution :)