PHP Warning: Undefined variable $conn

[Aruna KN]

Following code is working fine up to PHP 7.4 but with PHP 8.1 it makes an error_log: PHP Warning: Undefined variable $conn Please suggest me a solution for this issue. The relevant code line is:

if(!$conn) $conn = mysqli_connect(C_HOST,C_USER,C_PASS,C_BASE) or die($w[113]);

Full code of the function is:

function all_online_users()
{
if(!$conn) $conn = mysqli_connect(C_HOST,C_USER,C_PASS,C_BASE) or die($w[113]);

$sec = 300;
//exit;
if(isset($_SESSION['m']))
{
$user = is_numeric($_SESSION['m']) ? $_SESSION['m'] : 0;
$MyAccess = 0;

}
else
{
	$user = 0;
	$MyAccess = -1;
}
$ip = ($user == 0) ? ip2int(ip()) : 0;

mysqli_query($conn,"DELETE FROM ".C_MYSQL_ONLINE_USERS." WHERE (time < DATE_SUB(NOW(), INTERVAL ".$sec." SECOND) AND NOW() > ".$sec.") or time > NOW()");
$result = @mysqli_query($conn,"SELECT * FROM ".C_MYSQL_ONLINE_USERS);
$cnt=array();$adduser=1;$addguest=1;$users=0;
while($result && $i = mysqli_fetch_array($result))
{
$cnt[$i['usertype']] = (isset($cnt[$i['usertype']])) ? $cnt[$i['usertype']] + 1 : 1;
If(($MyAccess >= 0) && ($user == $i['user']))
{
$adduser=$addguest=0;
}
If(($MyAccess < 0) && ($ip == $i['ip']))
{
$adduser=$addguest=0;
}
}
if($adduser || $addguest)
{
mysqli_query($conn,"INSERT INTO ".C_MYSQL_ONLINE_USERS." VALUES (NOW(),".$user.",'".$MyAccess."','".$ip."')");
$cnt[$MyAccess] = (isset($cnt[$MyAccess])) ? $cnt[$MyAccess] + 1 : 1;
}
$k=0;while(isset($cnt[$k]))
{
$users = $cnt[$k] + $users;
$k++;
}
if(isset($cnt['-1'])) define('ONLINE_GUESTS',$cnt['-1']);
else define('ONLINE_GUESTS','0');
define('ONLINE_USERS',$users);
}

all_online_users();

[Lost User]

Try using the isset function:

if(!isset($conn)) ...

See PHP: isset - Manual[^]

[Aruna KN]

Thank you!