PHP函数的形参，实参

默认参数---------------------------------------------------------------------------------
function add_some_extra($args)
{
     $args['b']= "bbb";
}
$arr['a']= "aaa";
add_some_extra($arr);
fb::log($arr);
>>>>>>>>>> output>>>>>>>>>>>>>>

array(

        'a'=>'aaa',

)

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>


引用传递参数--------------------------------------------------------------------------
function add_some_extra(&$args)

{
     $args['b']= "bbb";
}
$arr['a']= "aaa";
add_some_extra($arr);
fb::log($arr);
>>>>>>>>>> output>>>>>>>>>>>>>>

array(

         'a'=>'aaa',

         'b'=>'bbb'

)

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

默认参数(参数为object时， 碉堡了。。。)----------------------------------------
function add_some_extra($args)
{
      $args->b ="bbb";
}
$obj->a = "aaa";
add_some_extra($arr);
fb::log($arr);
>>>>>>>>>> output>>>>>>>>>>>>>>

stdClass(

          a:'aaa',

          b:'bbb'

)

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

这个aObj会跟着变:
function aObj(&$a, &$b)
{
   $a = $b;
}
$a = new StdClass;
$a->i = 1;
$b = new StdClass;
$b->i = 2;
aObj($a, $b);
$b->i = 3;
print $a->i;

这个aObj一点都不变，还是i=1:
方程式aObj() 跟命令行_command_not_changed_相当:
function aObj($a, $b)
{
   $a = $b;
}
$a = new StdClass;
$a->i = 1;
$b = new StdClass;
$b->i = 2;
aObj($a, $b);
$b->i = 3;
print $a->i;

这个很详细的描述：
class testRefer{
    public $obj ;
   
    public function __construct(){
        $obj = new StdClass;
    }
   
    public function test($a, $b, &$aRef, &$bRef)
    {
       //$a = $b;              //$aOjb won't be changeed
       //$a->i = 10;           //$aOjb will be changeed to ->i=10
       //$a->i = $b->i;        //$aOjb will be changeed to ->i=2
       //$a = clone $b;        //$aOjb won't be changeed
      
       //$aRef = $bRef;        //$aOjb will always be changing follow bOjb
       //$aRef = $b;           //$aOjb will always be changing follow bOjb
       //$aRef->i = 10;        //$aOjb will be changeed to ->i=10
       //$aRef->i = $bRef->i;  //$aOjb will be changeed to ->i=2
       //$aRef = clone $bRef;  //$aOjb will be changeed to ->i=2
       
       //$a = $bRef;           //$aOjb won't be changeed
      
       $this->obj = $b;        // $testRefer->obj will always be changing follow bOjb
       //$this->obj = $bRef;   // $testRefer->obj will always be changing follow bOjb
    }
}


$aOjb = new StdClass;
$aOjb->i = 1;
$bojb = new StdClass;
$bojb->i = 2;

$testRefer = new testRefer();
$testRefer->test($aOjb, $bojb,$aOjb, $bojb);

$bojb->i = 3;

var_dump($aOjb);
print '
';
var_dump($bojb);
print '
';
var_dump($testRefer->obj);
print '
';


普通变量测试-------------------------------------------------------------------
function a(&$a, &$b)
 {
      $a =& $b;
 }
   $a = 1;
   $b = 2;
   a($a, $b);
   $b = 3;
print $a; 
这里输出 a=1

function a2(&$a, &$b)
{
   $a = $b;
}
$a = 1;
$b = 2;
a2($a, $b);
$b = 3;
print $a;
这里输出 a=2

方程式a() 跟以下命令行_command_not_changed_相当:

_command_not_changed_:
//a=1
$a = 1;
$b = 2;
$a1 =& $a;
$b1 =& $b;
$a1 = &$b1; //指向被改了
$b = 3;
这里输出 a=1
------------------------

//这个才会跟着变：
$a = 1;
$b = 2;
$a =& $b;
$b = 3;
print $a;
这里输出 a=1