Passing variable in curlopt_url - php

Question

I want to pass a variable in CURLOPT_URL, here is my code
$curl = curl_init();
curl_setopt_array($curl, array(
CURLOPT_URL => "https://api.postmates.com/v1/customers/cus_KtQih0aARUZXdk/deliveries/$delivery_id/cancel",
CURLOPT_RETURNTRANSFER => true,
CURLOPT_ENCODING => "",
CURLOPT_MAXREDIRS => 10,
CURLOPT_TIMEOUT => 30,
CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
CURLOPT_CUSTOMREQUEST => "POST",
CURLOPT_POSTFIELDS => array(
'pickup_address' => $_POST["pickup_address"],
'pickup_phone_number' => $_POST["pickup_phone_number"],
'pickup_name' => $_POST["pickup_name"],
'dropoff_address' => $_POST["dropoff_address"],
'dropoff_phone_number' => $_POST["dropoff_phone_number"],
'dropoff_name' => $_POST["dropoff_name"],
'manifest' => $_POST["manifest"]
),
CURLOPT_HTTPHEADER => array(
"authorization: Basic MjhiMDU0ODktNjdkYS00M2VhLTg0NmMtYWQ1MWQ2MGNmMDA1Og==",
"cache-control: no-cache",
"content-type: multipart/form-data; boundary=---011000010111000001101001",
),
));
$response = curl_exec($curl);
$err = curl_error($curl);
$delivery_id = trim($_POST['show_name']);
curl_close($curl);
$response = json_decode($response);
$timestamp = json_decode($dateJSON, true);
if ($err) {
echo "cURL Error #:" . $err;
} else {
echo $response->fee;
}
I want to add the variable $delivery_id in the url, but I am not too familiar with cURL and the above written code is not working. Please show me the way to include this variable in my url.

Answer 1

Once I had the same error. The solution is : use ' -apostrophe - and . -dot- before and after the variable. Like this:
/deliveries/'.$delivery_id.'/cancel