PHP Decimal128 string formating - php

Question

I am using MongoDB to store values as Decimal128 and using PHP with Twig to display them. My question is there a format the output with a thousands separator? I have tried using number_format, but that doesn't work because the value is a string not a int or float. I don't want to type cast the value because I want the value to be precision.
Examples:
1000.382 = 1,000.382
99.01 = 99.01
1900000 = 1,900,000
I wrote a function to do this. Still wondering if there is a better way to do it.
<?php
$n = '12345.001';
echo fNumString($n);
function fNumString ($number_string) {
$ex_num = explode('.', $number_string);
$whole_num_len = strlen($ex_num[0]);
$formated = '';
if ($whole_num_len > 3) {
for ($i = 0; $i < $whole_num_len; $i++) {
$formated .= $ex_num[0][$i];
if ((($whole_num_len - ($i + 1)) % 3) == 0 && $whole_num_len != ($i + 1))
$formated .= ',';
}
} else
$formated = $ex_num[0];
if (count($ex_num) == 2)
$formated .= '.' . $ex_num[1];
return $formated;
}

Answer 1

You could:
split the number string into integer and decimal parts using explode,
reverse the integer part using strrev,
add a thousands separator every 3 digits within that integer part using preg_replace,
reverse the integer part back using strrev,
return it concatenated with the decimal separator and the decimal part
Code:
function fNumString(string $numberString, string $decimalPoint = '.', string $thousandsSeparator = ','): string
{
[$integerPart, $decimalPart] = array_pad(explode('.', $numberString, 2), 2, null);
$integerPart = strrev(preg_replace('/\d{3}(?=\d)/', '\0' . $thousandsSeparator, strrev($integerPart)));
return $integerPart . ($decimalPart ? $decimalPoint . $decimalPart : '');
}
Demo: https://3v4l.org/m3jUC
Note: you could leave out the last 2 parameters of number_format, I like keeping them out for clarity (and in case they change the default values later for some reason).