How to use $_POST in another file - php

Question

I am making a panel with PHP. It contains a login script. It's working good, just what I expect. The next step is: Echo the username.
With $_POST you can echo the username what the person has typed. So, just like: Welcome, $username.
The problem now is, that I can't echo the $_POST. It's not possible because you will redirect to another page. My question is: How can I echo a username.
My login script:
<?php
//DATABASE CONNECTION
session_start();
$host = "localhost";
$username = "root";
$password = "root";
$database = "test_tutorial";
$message = "";
try {
$connect = new PDO("mysql:host=$host; dbname=$database", $username, $password);
$connect->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$fname = $_POST["fname"];
//LOGIN CHECK
if(isset($_POST["login"])) {
if(empty($_POST["fname"]) || empty($_POST["lname"])) {
echo 'All fields required';
}
else
{
$query = "SELECT * FROM users WHERE fname = :fname AND lname = :lname";
$statement = $connect->prepare($query);
$statement->execute(
array(
'fname' => $_POST["fname"],
'lname' => $_POST["lname"]
)
);
$count = $statement->rowCount();
if($count > 0)
{
//VISITED
header("Refresh:0; url=veilig.php");
//END
}
else
{
echo 'Wrong data';
}
}
}
}
catch(PDOException $error) {
$message = $error->getMessage();
}
?>
My form:
<form action="" method="post">
<label>fname</label>
<input type="text" name="fname" class="form-control" />
<br />
<label>lname</label>
<input type="password" name="lname" class="form-control" />
<br />
<input type="submit" name="login" value="Login" />
</form>
So, how can I echo a post if someone is redirected to another page?

Answer 1

You've already called session_start so you're ready to use the $_SESSION superglobal which will persist data for the user across all pages that call session_start first.
For example, here on index.php
<?php
session_start();
$_SESSION['username'] = 'Prabhjot.Singh';
header('Location: veilig.php');
Then later on veilig.php
<?php
session_start();
echo $_SESSION['username'];
Prabhjot.Singh