How to test a URL for 404 error in PHP?

<?php

// Creating a variable with an URL
// to be checked
$url = 'https://www.geeksforgeeks.org';

// Getting page header data
$array = @get_headers($url);

// Storing value at 1st position because
// that is only what we need to check
$string = $array[0];

// 404 for error, 200 for no error
if(strpos($string, "200")) {
    echo 'Specified URL Exists';
} 
else {
    echo 'Specified URL does not exist';
}

?>

<?php

// Initializing new session
$ch = curl_init("https://www.geeksforgeeks.org");

// Request method is set
curl_setopt($ch, CURLOPT_NOBODY, true);

// Executing cURL session
curl_exec($ch);

// Getting information about HTTP Code
$retcode = curl_getinfo($ch, CURLINFO_HTTP_CODE);

// Testing for 404 Error
if($retcode != 200) {
    echo "Specified URL does not exist";
}
else {
    echo "Specified URL exists";
}

curl_close($ch);

?>