return Json string not working - php

Question

I want to get data from api..
but I have trouble with json ..I can not get json string .. it print as normal string or xml..
I try multi method from net but no solution..
this my code:
$url = "http://fv4online.com/egov_api/v1/students/7";
$ch = curl_init();
curl_setopt($ch, CURLOPT_HTTPHEADER,array('Accept:
application/json;charset=UTF-8'));
// set url
curl_setopt($ch, CURLOPT_URL, $url);
//return the transfer as a string
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
// $output contains the output string
$output = curl_exec($ch);
print_r($output);
$t=json_decode($output,true);
print_r($t);
// close curl resource to free up system resources
curl_close($ch);
result of print ($output) is string:
7345345343testtesttesttest2000testliterary4564620171testDamascusar_lang300600350en_lang160400200fr_lang160400200national80200100history120300200geograph120300200philosophy160400300religion802001501700155060successful
and result of print(var_dump($output)) is xml:
'
7345345343testtesttesttest2000testliterary4564620171testDamascusar_lang<'... (length=1544)
note: Previously I was able to get this data without any problems, but suddenly the problem arose

Answer 1

That string contains all values the XML from the url returns, just without the tags around them. If you do 'View Source' you'll see more.
You get XML, not JSON. Could be they've changed that (which would be a bit odd, but I've seen worse). If you want is as JSON:
$xml = simplexml_load_string($xml_string);
$json = json_encode($xml);