Subdomain Scanner V2

<?php
function curl($url)
{
    $setopt = array(
        CURLOPT_URL => 'https://osint.sh/subdomain/',
        CURLOPT_RETURNTRANSFER => true,
        CURLOPT_POST => true,
        CURLOPT_POSTFIELDS => "domain=$url",
        CURLOPT_USERAGENT => 'Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.84 Safari/537.36',
        CURLOPT_TIMEOUT => 60,
        CURLOPT_CONNECTTIMEOUT => 60
    );
    $ch = curl_init();
    curl_setopt_array($ch, $setopt);
    $exe = curl_exec($ch);
    curl_close($ch);
    return $exe;
}
$domain = readline("Domain : ");
if (!empty($domain))
{
    $subdomain = curl($domain);
    $scrap = preg_match_all("/<a href=\"(.*?)\" target=\"_blank\">www.(.*?)<\/a>/i", $subdomain, $subdo);
    echo "\nResult : \n";
    for ($i = 0; $i < count($subdo[2]); $i++)
    {
        echo "[+] ".$subdo[2][$i]."\n";
        $result = fopen('result.txt', "a+");
        fwrite($result, $subdo[2][$i]."\n");
        fclose($result);
    }
    echo "\nTotal All Subdomain In Domain $domain : ".count($subdo[2]);
}
else
{
    echo "Domain Empty!!";
}
?>