I build four modules: Admin Home User Home ,and an Addons Then I create four router:
    $router->add("/index/:controller/:action/:params", array(
        'module'     => 'index',
        'controller' => 1,
        'action'     => 2,
        'params'     => 3,
    ));
    $router->add("/admin/:controller/:action/:params", array(
        'module'     => 'admin',
        'controller' => 1,
        'action'     => 2,
        'params'     => 3,
    ));
    $router->add("/home/:controller/:action/:params", array(
        'module'     => 'home',
        'controller' => 1,
        'action'     => 2,
        'params'     => 3,
    ));
    $router->add("/user/:controller/:action/:params", array(
        'module'     => 'user',
        'controller' => 1,
        'action'     => 2,
        'params'     => 3,
    ));if users input: Home/...or User/... or Index/... or Admin/... ,it will redirect to their modules,But users input anywords which is not in 'home,admin,user,index',it will redirect allows:
$router->add("**....**/:params.", array(
    'module'     => 'user',
    'controller' => 'addons',
    'action'     =>'excut',
    'addons'  =>'',(this is the head word)
    'params'     => 1,
));How to write the last router-string???Please help me