Non-empty string empty after return - php

Question

I'm writing a php script that deals with page processing via cURL, so I have a function to get and return pages by URL
function get_url($Url){
if (!function_exists('curl_init')){
die('Sorry cURL is not installed!');
}
set_time_limit (20);
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $Url);
curl_setopt($ch, CURLOPT_HTTPHEADER, array("Cookie: age_gate_birthday=19901101"));
curl_setopt($ch, CURLOPT_REFERER, "http://www.facebook.com");
curl_setopt($ch, CURLOPT_USERAGENT, "Mozilla/5.0 (Windows NT 6.3; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2049.0 Safari/537.36");
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$output = curl_exec($ch);
return $output;
}
echoing $output in this function always returns a string of HTML, however if I call on this function in another function
function get_vid ($sql, $url) {
$data = get_url($url);
...
the returned value is an empty string, despite the fact that $output had value when get_url() was doing its thing.
Weirdly enough, the error only exists with specific URLs, but works fine with others.
Thank you for trying to help!
UPDATE: It seems CURL returns FALSE randomly on specific links, which seems to be a culprit of this issue, however curl_error is empty, so I'm unable to identify the cause of this.

Answer 1

I think it's because you get a http redirect.
Try to check http code like this :
if (curl_getinfo($ch,CURLINFO_HTTP_CODE) == 302) {
// Manage http redirect here
}