Why is there an error connecting to the database?

Question

PHP

What a nonsense. If I specify the root login directly, then it connects. And if I pass it through a variable, I get the following error Warning: mysqli_connect(): (HY000/1045): Access denied for user ''@'localhost' (using password: NO) in C:\openserver\OSPanel\domains\darkdate\ www\modules\config.php on line 9
who can tell me what's wrong?
this is how it works

and this is how it throws an error

Answer 1

Your variables are declared outside of the function.
There are three solutions:
1. The function must accept arguments, and when called, you will pass them ( recommended ):

function connect($server, $login, $password, $db) {
    return mysqli_connect($server, $login, $password, $db)
}

$connection = connect($server, $login, $password, $db);

2. The function will retrieve variables from the global scope:

function connect() {
    global $server;
    global $login;        
    global $password;
    global $db;

    return mysqli_connect($server, $login, $password, $db);
}

$connection = connect($server, $login, $password, $db)

3. The function will be anonymous and retrieve data from the local scope:

$connect = function() use ($server, $login, $password, $db) {
    return mysqli_connect($server, $login, $password, $db);
};

$connection = $connect();

PS When creating questions, copy the code, do not paste screenshots.