PHP determines whether the request is HTTPS

Some time ago, the company needed to be compatible with users using HTTPS websites, so it was necessary to dynamically determine whether the request initiated by the user was https. The code is as follows:

if ($_SERVER["HTTPS"] != "on"){
    $http = 'http';
}else{
    $http = 'https';
}

The above introduces PHP to determine whether the request is HTTPS, including the relevant aspects. I hope it will be helpful to friends who are interested in PHP tutorials.