<?php
error_reporting(-1);
$str = file_get_contents('https://www.google.com/finance?q=USDEUR');

$stringOfRate = array();
$regexp = '/1\\s([A-Z]{3})\\s[=]\\s([0-9]+)[.]([0-9]+)/ui';
preg_match($regexp, $str, $stringOfRate);

var_dump($stringOfRate);