....

string

<?php
$q=" !";
print $q;
exit;
?>

   , $q  ,          " !"



<?php
$q[""]=array("name"=>"");
print $q[""]["name"];
?>

     .    ,   ,    .



<?php
class name
{
    function funct1()
    {
        print "Hello world!";
    }
}
$q=new name();
$q->funct1();
?>

      name   funct1   
    "hello world!".           
    funct1.



 -   ,      .

Null

<?php
$q="Helloy world!";
$q=NULL;
print $q;
exit;
?>

           , 
     $q  ,     "Helloy world!".

callback

<?php
function funct1()
{
    print "Helloy world!";
}
call_user_func('funct1');
?>

        ,    .

  !