php函数将结果返回到数组变量中

I have 2 files named login.php and configDb.php . I have a function named sql_query($query) in configDb.php somehow like this:

function sql_query($query) {
$link=mysqli_connect("localhost", "root", "", "basheer");
if (mysqli_connect_error()) {
    echo mysqli_connect_errno();
}
$q=  mysqli_query($link, $query);
while ($row=mysqli_fetch_array($q))
{   
       return $row['username']." ".$row['password'];
}
}

I included file in login.php and I am able to fetch the result in an array variable:

$username = $_POST['user'];//
$password = $_POST['pass'];
$query="select * from tbladmin where username='Admin'";//Sql query
require  'include/config_db.php';
$user=  sql_query($query);//passed the function result to an array var
print_r($user);//prints the result correctly
echo '<br/>';
if ($username == $user['username'] && $password == $user['password'])
//I am stuck here with $user['username] and $user['password'] 
{
   header("location: index.php");
} else {
    $message = "Invalid user name or password, please try again!";
}

How to compare $username and $password with $user array variable ?

Make your function return an array instead of a string

Change:

return $row['username']." ".$row['password'];

To:

return array("username" => $row['username'], "password" => $row['password']);

you must return an array : return $row; and not $row['username']." ".$row['password']; it's a string

<?php
    session_start();
    require_once('connectie.php');

    if(isset($_POST['submit'])){
        $username = strip_tags($_POST['username']);
        $password = strip_tags($_POST['password']);

        $username = $db->real_escape_string($username);
        $password = $db->real_escape_string($password);

      $sql = "SELECT id, username, password FROM gebruikers WHERE username = '$username' AND password = '$password'";

      $result = $db->query($sql);

      if($result->num_rows == 1){
        $row = $result->fetch_object();
        $_SESSION['loggedin'] = true;
        $_SESSION['id'] = $row->id;
        $_SESSION['username'] = $row->username;

        print_r($result);
        header('location: ../index.php ');

      }else{
        session_destroy();
        echo "NOPE";
      }
    }
?>

This is what i'm using in my login system.

Best choice is to compare your POST parameter with the username and password exist in database and get the count. If count is 1 its mean authentication success. else return 0

$query = "select count(*) from tbname where username = '".$_POST['username']."' and password = '".$_POST['password']."'";
$run = mysqli_query($query);
$result = mysqli_fetch_array($run);
if($result['count']==1){
    header("location: index.php");
}else{
    $message = "Invalid user name or password, please try again!";
}