Hashed password not coming out to what it should be (PHP)

Question

So I'm trying to make a fairly simple login system, but for some reason the hashed password that is being sent to my database is not hashing correctly. I checked my database and the stored password is not what the sha256 hashed with the generated salt appended is not what it's supposed to be. Here's my code for generating the hash that's being uploaded to the database:

<?php
include "connection.php";
//Check Connection
if ($connect->connect_error) {
    echo "Failed to connect to server: " . mysqli_connect_error();
}

//Reset all Checks
$username_exists = NULL;
$email_valid = NULL;
$passwords_match = NULL;
$password_acceptable = NULL;
$password_long_enough = NULL;
$password = NULL;

//Prepare Statements
    //Check for Username Existing Statement
    $check_username_match = $connect->stmt_init();
    $sql_check_username = "SELECT id FROM $tablename WHERE username=?";
    $check_username_match->prepare($sql_check_username);
    $check_username_match->bind_param("s", $username);

    //Insert Into Table Statement
    $register_query = $connect->stmt_init();
    $sql_register = "INSERT INTO $tablename (username, email, password, token, active, level) VALUES (?, ?, ?, ?, ?, ?)";
    $register_query->prepare($sql_register);
    $register_query->bind_param("sssssi", $username, $email, $hashedpassword, $token, $activated, $level);

//Execute When Form Submitted
if($_SERVER["REQUEST_METHOD"] == "POST") {
    $username = mysqli_escape_string($connect, $_POST['username']);
    $email = mysqli_escape_string($connect, $_POST['email']);
    $password = $_POST['password'];
    $confirm_password = $_POST['confirm_password'];

    //Check if Username Exists
    $check_username_match->execute();
    $check_username_match->store_result();
    $numrows = $check_username_match->num_rows;
    if ($numrows==0){
        $username_exists = false;
    } else {
        $username_exists=true;
    }

    //Check if Passwords Match
    if ($password==$confirm_password){
        $passwords_match = true;
    } else {
        $passwords_match = false;
    }

    //Check if Email Address is Valid
    if (filter_var($email, FILTER_VALIDATE_EMAIL)) {
        $email_valid = true;
    } else {
        $email_valid = false;
    }

    //Check if Passwords Contains Special Characters
    $uppercase = preg_match('@[A-Z]@', $password);
    $lowercase = preg_match('@[a-z]@', $password);
    $number    = preg_match('@[0-9]@', $password);
    //Check if Password is Long Enough
    $password_length = strlen($password);
    if ($password_length>8){
        $password_long_enough = true;
    } else {
        $password_long_enough = false;
    }

    //Validate Password
    if(!$uppercase || !$lowercase || !$number || !$password_long_enough || $password = '') {
        $password_acceptable = false;
    } else {
        $password_acceptable = true;
    }

    //Register if all Validations Met
    if(!$username_exists && $email_valid && $passwords_match && $password_acceptable){
        //$salt = dechex(mt_rand(0, 2147483647)) . dechex(mt_rand(0, 2147483647));
        $token = dechex(mt_rand(0, 2147483647)) . dechex(mt_rand(0, 2147483647));
        $activated="No"; 
        $level = 0;
        $hashedpassword = password_hash($password, PASSWORD_DEFAULT);
        $register_query->execute();
        $message = "Hello, welcome to the site.\r\n\r\nPlease click on the following link to activate your account:\r\nlocalhost/login_system/activate.php?token=".$token;
        mail($email, 'Please Activate Your Account', $message);
        header("Location: login.php");
    }
}
?>

UPDATE: I changed my above code to reflect the changes I made with password_hash. However, the problem still persists.

This is my login php:

<?php
include("connection.php");
session_start();
//Reset Variables
$message = '';
$location = "/login_system/index.php"; //default location to redirect after logging in
$username = '';
$password = '';

//Check to see if user is newly activated; if he is display a welcome message.
    if(isset($_GET['activated'])){
        if($_GET['activated'] == "true"){
            $message = "Thank you for verifying your account. Please login to continue.";
        }
    }

//Check to see if user is coming from another page; if he is then store that page location to redirect to after logging in.
if(isset($_GET['location'])) {
    $location =  htmlspecialchars($_GET['location']);
}

echo $location;

//Prepare login check statement
    $check_login = $connect->stmt_init();
    $sql = "SELECT id, password FROM $tablename WHERE username=?";
    $check_login->prepare($sql);
    $check_login->bind_param("s", $username);

//Execute Login Check
    if($_SERVER["REQUEST_METHOD"] == "POST") {
        $username = mysqli_escape_string($connect, $_POST['username']);
        $password = $_POST['password'];
        $check_login->execute();
        $check_login->store_result();
        $numrows = $check_login->num_rows;
        $check_login->bind_result($id, $match);
        $check_login->fetch();
        if ($numrows==1 && password_verify($password, $match)) {
            $_SESSION['login_user'] = $id;
            $goto = "localhost".$location;
            header("location: $goto");
            $message = "Success!";  
        } else {
            $message="Username or password is not valid."."<br>".$match."<br>";
        }
    }
    $connect->close();
?>

Answer 1

You should just feed the password you want to hash into PHP's password_hash();function. Like so...

$password = $_POST['password'];

$options = [
    'cost' => 12,
];
echo password_hash($password, PASSWORD_BCRYPT, $options);

Then when you want to check if the password exists in the database use password_verify(); Like so...

$password = PASSWORD_HERE;
$stored_hash = HASH_HERE;

if (password_verify($password, $stored_hash)) {
    echo 'Password is valid!';
} else {
    echo 'Invalid password.';
}