namespace userCenter;
//php代码
namespace userCenter\register;
//php代码
namespace userCenter\login {
 //php代码
}

\userCenter\register; //绝对调用
userCenter\login; //相对调用
use userCenter\register; //引用空间
use userCenter\register as reg; //引用空间并加别名

<"login OK<br>";
}
class login{
 public function save(){
 echo "login had saved<br>";
 }
}
"htmlcode">

<"regist OK<br>";
 }
 class regist{
 public function save(){
 echo "regist had saved<br>";
 }
 }
}
"htmlcode">

<"login.class.php";
require "regist.class.php";
use userCenter\regist; //使用use调用空间
use userCenter\regist as reg; //as定义别名
echo \userCenter\check_username(); //绝对调用
$login = new \userCenter\login();
echo $login->save();
echo regist\check_username(); //相对调用
echo reg\check_username(); //别名调用
$regist = new reg\regist();
echo $regist->save();




使用use，比绝对调用要好一点，好比给class,function等加了一个前缀，这样看起来就比较清楚了。
希望本文所述对大家PHP程序设计有所帮助。