substr and mb_substr return nothing - php

Question

I do not know what is wrong in the code below:
<?php
$html = file_get_contents('https://www.ibar.az/en/');
$doc = new domDocument();
$doc->loadHTML($html);
$doc->preserveWhiteSpace = false;
$ExchangePart = $doc->getElementsByTagName('li');
/*for ($i=0; $i<=$ExchangePart->length; $i++) {
echo $i . $ExchangePart->Item($i)->nodeValue . "<br>";
}*/
$C=$ExchangePart->Item(91)->nodeValue;
var_dump ($C);
$fff=mb_substr($C, 6, 2, 'UTF-8');
echo $fff;
?>
I have tried both substr and mb_substr but in both cases echo $fff; returns nothing.
Could anybody suggest what I am doing wrong?

Answer 1

This is the item 91 node:
<ul>
<li>USD</li>
<li>1.5072</li>
<li>1.462</li>
<li>1.5494</li>
<li class="down"> </li>
</ul>
This is node value:
¶
····························USD¶
································1.5072¶
································1.462¶
································1.5494¶
································•¶
····························
( · = space; • = nbsp )
substr( $C, 6, 2 ) is a string of two spaces.
To correct retrieve all values:
foreach( $ExchangePart->Item(91) as $node )
{
if( trim($node->nodeValue) ) echo $node->nodeValue . '<br>';
}
Otherwise, you can replace all node value spaces:
$C = str_replace( ' ', '', $C );