PHP的问题获取内容+ API

I am trying to create an Adfly shortener website for my associates to use using PHP. I thought this would be simple, but I am having some trouble getting this to work

$longURL = $_GET['longurl'];

$shortURL = shortAdfly($longURL);

// Print the result
print_r($shortURL);

// Adf.ly shortener
function shortAdfly($ToConvert) {
    urlencode($ToConvert);
    $apiUrl = 'http://api.adf.ly/api.php?' . http_build_query([
    'key' => 'My API Key',
    'uid' => 'My User ID',
    'advert_type' => 'int',
    'domain' => 'adf.ly',
    'url' => $ToConvert ]);
    $short_url = file_get_contents($apiUrl);
    return $short_url;
}

Building URL query strings by hand is like encoding JSON by hand; you just shouldn't do it. Use the tools provided

$apiUrl = 'http://api.adf.ly/api.php?' . http_build_query([
    'key'         => 'your-api-key',
    'uid'         => 1234567,
    'advert_type' => 'int',
    'domain'      => 'adf.ly',
    'url'         => $ToConvert
]);
return file_get_contents($apiUrl);