被PDO中的致命错误所困扰？ [关闭]

I'm receiving a Fatal error output to my webpage. This is the error:

Fatal error: Uncaught exception 'PDOException' with message 'SQLSTATE[HY000] [2005] Unknown MySQL server host '$host' (20)' in /Users/aaronwilson/Desktop/testing_server/ATOM_CMS/config/setup.php:14 Stack trace: #0 /Users/aaronwilson/Desktop/testing_server/ATOM_CMS/config/setup.php(14): PDO->__construct('mysql:host=$hos...', 'atomcmsadmin', '**') #1 /Users/aaronwilson/Desktop/testing_server/ATOM_CMS/config/setup.php(22): dbConnect('atomcmsadmin', '**', 'localhost', 'Atom_CMS') #2 /Users/aaronwilson/Desktop/testing_server/ATOM_CMS/index.php(2): include('/Users/aaronwil...') #3 {main} thrown in /Users/aaronwilson/Desktop/testing_server/ATOM_CMS/config/setup.php on line 14

Here is the code that is triggering the error on my Setup.php page:

<?php ## Setup Document

// host(or location of the database), username, password, database name
//Variables for connecting to your database.
//These variable values come from your hosting account.

error_reporting(E_ALL);
ini_set('display_errors', 1);
require('functions/sandbox.php');

$host = "localhost";
$user = "atomcmsadmin";
$pass = "*******";
$dbname = "Atom_CMS";

//Connecting to your database

function dbConnect($user, $pass, $host, $dbname) {
$dbc = new PDO('mysql:host=$host;dbname=$dbname', $user, $pass);

try {
    global $dbc;
    }
catch (PDOException $e) {
    echo $e->getMessage();
}
}
if (dbConnect($user, $pass, $host, $dbname)) {
print('worked');
}

if ($_GET ['page'] == '') {
$pg = 'home';} 
else {
$pg = $_GET ['page']; }
$page_title = get_title($dbc, $pg);
?>

Any suggestions would be appreciated.. :)

In this line:

$dbc = new PDO('mysql:host=$host;dbname=$dbname', $user, $pass);

You have used single quotes. PHP doesn't expand variables in strings where single quotes have been used, so PDO sees the hostname as $host.

Try

$dbc = new PDO("mysql:host=$host;dbname=$dbname", $user, $pass);
               ^                               ^ // note double quotes.