problem with search

[eluser]huuray[/eluser]
hi all,
looked the forum,google.com,but no luck with search with space "code igniter"

Code:

function search()
{        
echo $this->uri->segment(3);
}

when i try to browse http://localhost/user/search/code igniter , it will return code_igniter

any idea?
sorry for my poor english