 ()


  PHP       .     .
     ,      PHP.                ,         : '[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*'
:      -  a-z, A-Z,  ASCII-  127  255 (0x7f-0xff).

<?php 
$var = "Bob";
$Var = "Joe";
echo "$var, $Var";      //  "Bob, Joe"
$4site = 'not yet';     // ;   
$_4site = 'not yet';    // ;    
$tyte = 'mansikka';    // ; ''  () ASCII 228.
?>

 PHP 3     .  ,     ,        .  ,  ,       ,         .          .
PHP 4      :   .  ,      ( , " "  "")   .       ,  .   ,    ;  ,   . ,                 .
   ,    (&)     () . ,      'My name is Bob':
<?php
$foo = 'Bob';              //  $foo  'Bob'
$bar = &$foo;              //   $foo  $bar.
$bar = "My name is $bar";  //  $bar...
echo $bar;
echo $foo;                 //   $foo.
?>

 ,         .
<?php
$foo = 25;
$bar = &$foo;      //   .
$bar = &(24 * 7);  // ;    .

function test()
{
   return 25;
}
$bar = &test();    // .
?>