Composer自动加载器

Question

I'm trying to learn composer, but I can't seem to get the autoloader to work with a package I've created. It just states that the class could not be found.

What am I doing wrong?

Index.php:

require 'vendor/composer/autoload_psr4.php';
use packageName\core\Bootstrap;
$boot = new Bootstrap();

Bootstrap.class.php (inside /vendor/vendorName/packageName/core/):

namespace packageName\core;
class Bootstrap {
   ...

composer.json for packageName:

"autoload": {
    "psr-4": { "packageName\\core\\": "/vendor/vendorName/packageName/core" }
}

Answer 1

Mark Baker's answer (in the comments above) fixed the problem.

"Is /vendor/... really at root level in your filesystem? If it's a relative path rather than an absolute path, use "vendor/vendorName/packageName/core"