namespace Example;
require_once "fnction.php";
class ClassA {}
function Function() {}
//完全限定名称
ExampleFunction();
ExampleBFunction(); 
//限定名称
BFunction(); //指向 ExampleBFunction();
//非限定名称
$test = new ClassA(); //resolves to ExampleClassA
Function(); //指向 ExampleFunction

namespace FooBarsubnamespace;
const FOO = 1;
function foo() 
{
  return "foorn";
}
class foo 
{
  static function staticmethod()
  {
    return __METHOD__ . "rn" ;
  }
  function foofunction()
  {
    return __METHOD__ . "rn" ;
  }
}

namespace secondsp;
include 'function.php';
class foo
{
  function foofunction()
  {
    return __METHOD__ . "rn" ;
  }
}
function is_file($file)
{
  return true ;
}
//非限定名称:实例化secondspfoo类对象
$obj = new foo; 
echo $obj->foofunction();
//实例化FooBarsubnamespacefoo 类对象
$obj = new FooBarsubnamespacefoo ;
echo $obj->foofunction();
//代码会报错，在命名空间内部，假如无法找到当前命名空间下的类，则会报错
//$obj = new ArrayObject(array(1)); 
$obj = new ArrayObject(array(1)); 
//在命名空间内部，假如无法找到当前命名空间下的函数或者常量，则会寻找 native function
echo strlen("nihao");
 //引用当前命名空间下的函数
var_dump(is_file('nihao')); //True
//引用全局函数
var_dump(is_file('nihao')); //False

include 'function.php';
use FooBarsubnamespacefoo ;
$obj = new foo;
echo $obj->foofunction();
use FooBarsubnamespacefoo as aliasfunname;
$obj = new aliasfunname;
echo $obj->foofunction();
use FooBarsubnamespace ; 
$obj = new subnamespacefoo ;
echo $obj->foofunction();
use FooBarsubnamespace as aliasname;
$obj = new aliasnamefoo ;
echo $obj->foofunction();
//由于调用代码并不在命名空间内，所以对于全局的类，无需引入使用
$obj = new ArrayObject(array(1)); 
//导入一个函数
use function FooBarsubnamespacefoo  ;
echo foo();
use function FooBarsubnamespacefoo as func;
echo func();
use const FooBarsubnamespaceFOO;
//echo FOO;